WHARVES  AND  PIERS 


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Metallurgical  and  Chemical  Engineering  Power 


WHARVES  AND  PIERS 

THEIR  DESIGN,  CONSTRUCTION, 

AND 
EQUIPMENT 


BY 


CARLETON  GREENE,   A.B.,   C.E. 

MEMBER   AMERICAN  ^s'oCIETY    OF    CIVIL   ENGINEERS 


FIRST  EDITION 


McGRAW-HILL   BOOK   COMPANY,   INC. 

239  WEST  39TH   STREET,   NEW  YORK 


LONDON:   HILL  PUBLISHING  CO.,  LTD. 

6  &  8  BOUVERIE  ST.,  E.  C. 

1917 


COPYRIGHT,    1917  BY  THE 
MCGRAW-HILL   BOOK   COMPANY,   INC. 


PEEFACE 

THIS  book  has  been  written  in  response  to  an  editorial  in 
one  of  the  engineering  journals  calling  attention  to  the  lack 
of  American  books  on  the  subject  of  Wharves  and  Piers. 
In  its  preparation  the  author  has  therefore  endeavored  to 
present  a  treatise  on  modern  American  practice  in  the  de- 
sign and  construction  of  wharves,  piers,  pier-sheds  and  their 
equipment,  including  machinery  for  handling  miscellaneous 
package  freight. 

The  subject*of  pile  driving  has  not  been  gone  into  deeply 
as  it  has  been  treated  at  length  in  Jacoby  and  Davis'  recent 
work  on  " Foundations  of  Bridges  and  Buildings." 

It  is  the  writer's  opinion  that  there  is  a  tendency  at  the 
present  time  to  slight  the  advantages  of  timber  construction 
for  wharves  and  to  overestimate  those  of  reinforced  con- 
crete. As  the  principles  and  methods  requisite  for  dura- 
bility in  wooden  wharf  construction  have,  as  far  as  the 
writer  knows,  not  been  set  forth  in  book  form  they  have 
been  given  particular  attention  in  this  volume. 

While  most  of  the  descriptions  and  illustrations  of  ex- 
isting structures  have  necessarily  been  collected  from  the 
technical  press,  for  which  no  originality  is  claimed,  an 
attempt  has  been  made  to  emphasize,  in  describing  such 
structures,  the  particular  conditions  which  had  to  be  pro- 
vided for  in  the  design,  the  methods  used  for  fulfilling  the 
special  requirements  and,  to  some  extent,  the  reasons  why 
particular  types  and  details  were  adopted.  It  is  believed 
that  such  descriptions  will  aid  designers  in  solving  prob- 
lems which  embrace  similar  conditions. 


360385 


viii  PREFACE 

For  information  in  regard  to  European  practice  in  the 
construction  of  wharves  and  piers  the  reader  is  referred  to 
"Seehafenbau"  by  F.  W.  Schulze:  Berlin,  Ernst  &  Sohn 
1913,  and  for  further  information  in  regard  to  the  New 
York  practice  in  freight  handling  to  the  Report  on  the 
" Mechanical  Equipment  of  New  York  Harbor"  by  B.  F. 
Cresson,  Jr.,  and  Chas.  W.  Staniford  and  to  other  reports 
published  by  the  Department  of  Docks.  In  Fowler's 
" Subaqueous  Foundations"  may  be  found  examples  of  the 
wooden  piers  of  the  Pacific  Coast  and  in  the  latest  edition 
of  Merriman's  "  American  Civil  Engineers'  Pocket  Book" 
there  is  much  valuable  information  in  condensed  form. 

Acknowledgments  are  due  to  Mr.  Charles  W.  Staniford, 
Chief  Engineer  of  the  Department  of  Docks,  New  York, 
N.Y.,  and  to  the  other  officials  of  that  department  for 
photographs,  drawings  and  information;  to  Mr.  S.  W.  Hoag, 
Jr.,  for  permission  to  reprint  portions  of  his  paper  on  New 
York  docks,  published  in  the  proceedings  of  The  Municipal 
Engineers  of  New  York,  to  Engineering  News,  Engineer- 
ing Record,  Engineering  Contracting  and  International  Marine 
Engineering,  also  to  the  General  Electric  Co..  Lidgerwood 
Mfg.  Co.,  Brown  Portable  Elevator  Co.,  J.  Edward  Ogden 
Co.,  American  Engineering  Co.  and  others  for  illustrations. 

C.  G. 

NEW  YORK, 
January,  1917 


CONTENTS 


PAGE 

PREFACE  .  vii 


CHAPTER  I.  —  INTRODUCTION 

DEFINITIONS 1 

REQUIREMENTS 2 

TYPES 3 

MATERIALS  OF  CONSTRUCTION 4 

Timber 4 

Wood  Preservatives 9 

Concrete 11 

Concrete  Piles      13 

Stone  Masonry 14 

Steel 14 

Cast  Iron 16 

Riprap 17 

Concrete  vs.  Timber 17 

CHAPTER  II.  —  PRIMARY  PRINCIPLES  OF   DESIGN 

COMMERCIAL  LIFE 19 

GROWTH  OF  SHIPS 22 

MARGINAL  WHARVES  vs.  PIERS •  .    .  23 

DIMENSIONS  OF  WHARVES 24 

LIVE  LOADS 26 

TIDAL  PRISM 26 

CHAPTER  III.  —  DETAILS  OF  TIMBER  CONSTRUCTION 

PILES  AND  PILE  DRIVING 28 

Pile  Formulas 28 

Steam  vs.  Drop  Hammers      .    .    .    .    ; 29 

Lagged  Piles 29 

Floating  Drivers      29 

Inclined  Drivers      . 30 

Pile  Followers 31 

LATERAL  SUPPORT  FOR  PILES 31 

TEST  PILES  AND  BORINGS 32 

DETAILS  OF  CONSTRUCTION 33 

IRON  AND  WOOD  FASTENINGS 40 

SEWERS  IN  PIERS  42 


x  CONTENTS 

CHAPTER  IV.  —  RETAINING  WALLS  FOR   PIERS  AND 
MARGINAL   WHARVES 

FUNCTIONS  OF  WALLS 43 

CALCULATION  OF  PRESSURES 43 

Mud  Waves 48 

GRAVITY  WALLS 48 

Riprap 49 

New  York 50 

Design  for  a  Cheap  Riprap  Wall  with  Pile  Platform 51 

San  Francisco 52 

Cribwork 52 

N.  Y.  Dock  Department 53 

Communipaw,  Jersey  City,  N.  J 54 

N.  Y.  Barge  Canal 56 

Duluth,  Minn 56 

Two  Harbors,  Minn 57 

Buffalo,  N.  Y 58 

Oswego,  N.  Y 59 

Hoboken,  N.  J 59 

Depot  Harbor,  Ont 60 

Quarried  Stone  Wails 61 

Boston,  Mass.' 61 

Concrete  Block  Walls 62 

52nd  St.,  New  York,  N.  Y 64 

East  102nd  St.,  New  York,  N.  Y 65 

Halifax,  N.  S 66 

Mass  Concrete  Walls 69 

East  116th  St.,  New  York,  N.  Y 70 

N.  Y.  Barge  Canal 71 

Oakland,  Cal 71 

San  Diego,  Cal 71 

Floating  Caissons    . 71 

Copenhagen,  Denmark 71 

Norre  Sundby,  Denmark 72 

Welland  Canal,  Ont 72 

Victoria,  B.  C 74 

Algoma,  Wis 76 

RELIEVING  PLATFORM  WALLS 76 

Gowanus  Bay,  Brooklyn,  N.  Y 77 

Hunt's  Point,  New  York,  N.  Y 79 

Wallabout  Bay,  Brooklyn,  N.  Y 82 

Los  Angeles,  Cal 82 

Providence,  R.  1 83 

Whale  Creek,  Brooklyn,  N.  Y 84 

Schenectady,  N.  Y 85 

Whitehall,  N.  Y 85 


CONTENTS  xi 

Savannah,  Ga 85 

Rio  Janeiro,  Brazil 86 

Bush  Terminal,  Brooklyn,  N.  Y 86 

New  York,  N.  Y.  Type  of  1876 ' 88 

New  York,  N.  Y.  Type  of  1899 92 

East  23rd  St.,  New  York,  N.  Y 94 

Rector,  St.  New  York,  N.  Y 95 

Chicago,  111 96 

Don  River,  Toronto,  Ont 97 

Toledo,  O 97 

Detroit,  Mich 97 

Cleveland,  0 98 

Hamilton,  Ont 98 

Jacksonville,  Fla.   . 101 

SHEET-PILE  WALLS 103 

Chicago,  111 104 

Black  Rock,  Buffalo,  N.  Y 104 

Sandusky,  0 105 

Ashtabula,  O  .    .    : 105 

Rome,  N.  Y 108 

Baltimore,  Md 108 

Raymond's  Patent 110 

CHAPTER  V.  —  PIERS 

COMPARISON  OF  TYPES 112 

Pile  Platform 112 

Block  and  Bridge 112 

Solid  Fill 112 

PILE  PLATFORM  PIERS 114 

Classification ^. 114 

Advantages  of  Different  Classes 114 

Examples  of  Typical  Piers 116 

1.  Wood  Piles  extending  up  to  deck 116 

(a)  Wooden  Deck 

N.  Y.  Dock  Dept.  Standard 118 

North  German  Lloyd,  New  York 118 

Pacific  Coast  Type 119 

B.  &  A.  R.  R.,  Boston,  Mass 119 

(6)  Concrete  Deck 

New  London,  Conn 120 

New  York  33d  St.,  South  Brooklyn 123 

C.  R.  R.  of  N.  J.,  Jersey  City,  N.  J 124 

(c)  Concrete  Caps  and  Deck 

Commonwealth  Pier,  No.  5,  Boston,  Mass 125 

2.  Wood  Piles  cut  off  near  Low  Water 

(a)  Fill  on  Platforms 

D.,  L.  &  W.  R.  R.  Pier  No.  9,  Hoboken,  N.  J 126 


xii  CONTENTS 

(6)  Concrete  Posts  or  Cross  Walls 

Navy  Yard,  Brooklyn,  N.  Y 127 

Piers  38  and  40,  Philadelphia,  Pa 128 

3.  Composite  Piles  of  Wood  and  Concrete 

Bocas  del  Toro,  Panama 128 

San  Francisco,  Cal 131 

Port-au-Prince,  Haiti 131 

San  Juan,  Porto  Rico 132 

4.  Metal  Piles  or  Cylinders 

(a)  Cast  Iron  Piles 

Fort  Monroe,  Va 133 

(6)  Wrought  Iron  or  Steel  Piles 

Lambert's  Point,  Va 133 

Coney  Island,  New  York,  N.  Y 133 

Atlantic  City,  N.  J 134 

Old  Orchard,  Me 134 

(c)  Wrought  Iron  or  Steel  Cylinders 

Tampico,  Mexico 134 

Manila,  P.  1 135 

Lambert's  Point,  Va 136 

(d)  Cast  Iron  Cylinders 

Cienfuegos,  Cuba 136 

5.  Reinforced  Concrete  Piles 

Brunswick,  Ga 136 

Charleston,  S.  C 137 

Atlantic,  City  N.  J 138 

Santa  Monica,  Cal 138 

Long  Branch,  N.  J 139 

Oakland,  Cal 140 

Halifax,  N.  S 141 

Havana,  Cuba 143 

6.  Reinforced  Concrete  Columns 

Piers  38  and  40,  San  Francisco,  Cal 147 

Ft.  Mason,  San  Francisco,  Cal 149 

Olongapo,  P.  1 150 

Puget  Sound  Navy  Yard 151 

Iloilo,  P.  1 152 

Balboa,  C.  Z. 152 

BLOCK  AND  BRIDGE  PIERS 154 

New  York 154 

Glen  Cove,  N.  Y 154 

SOLID  FILLED  PIERS 155 

Bush  Terminal,  Brooklyn,  N.  Y 155 

Dept.  of  Docks,  N.  Y 155 

Commonwealth  Pier  No.  6,  Boston,  Mass 156 

Victoria,  B.  C '. 156 

Halifax,  N.  S 156 

Marquette,  Mich 157 

Duluth,  Minn 158 


CONTENTS  xiii 

CHAPTER  VI.  —  WHARF  AND  PIER  SHEDS 

SHEDS  IN  GENERAL 159 

FIRE  RESISTING  CONSTRUCTION 162 

FRAMING      165 

SIDE  COVERINGS 166 

ROOFING      167 

LIGHTING  AND  VENTILATING      168 

DOORS      169 

PROTECTION  AGAINST  DAMAGE  AND  ACCIDENT 173 

EXAMPLES  OF  TYPICAL  SHEDS 174 

Plank  Shed  Truss 174 

Steel  Shed  Truss 174 

Two  Story  Timber  Shed,  Seattle,  Wash 174 

Steel  shed  33rd  St.  Pier,  S.  Brooklyn,  N.  Y 176 

Steel  shed  35th  St.  Pier,  S.  Brooklyn,  N.  Y 177 

Reinforced    Concrete    Shed,    Pier    No.   9,    D.,  L.  &  W.  R.  R., 

Hoboken,  N.  J 178 

Reinforced  Concrete  Shed,  Havana,  Cuba 178 

Steel  Shed  with  overhanging  Trusses,  N.  Y.,  N.  H.  &  H.  R.  R. 

piers,  New  York,  N.  Y 179 

Timber  Shed  Truss,  Los  Angeles,  Cal 179 

Steel  Shed  Truss,  Los  Angeles,  Cal 179 

Steel  Frame  Shed  with  Concrete  Roof  and  Siding,  San  Francisco  180 

Steel  Sheds,  Chelsea  Piers,  New  York,  N.  Y 180 

Reinforced  Concrete  Shed,  Halifax,  N.  S.     . 180 

Two-Story  Steel  Shed,  46th  Street,  New  York,  N.  Y 181 

CHAPTER  VII.  —  EQUIPMENT  OF  WHARVES   AND   PIERS 

FENDERS     183 

MOORING  DEVICES 187 

WHARF  DROPS 190 

PAVEMENTS 191 

RAILROAD  TRACKS 192 

FIRE  PROTECTION     194 

Fire  Walls 195 

Sprinklers 196 

Roof-Hydrants 198 

Fire  Resisting  Materials 198 

Automatic  Fire  Alarms      198 

Miscellaneous  Equipment 198 

CHAPTER  VIII.  —  CARGO  HANDLING   MACHINERY 

GENERAL  CONSIDERATIONS 20° 

Object 20° 


xiv  CONTENTS 

Function 200 

Operations  to  be  Performed 201 

Classification  of  Vessels 202 

Heavy  Packages 203 

CLASSIFICATION  AND  DESCRIPTION  OF  MACHINERY  AND  APPLIANCES  .  203 

Ship's  Gear 204 

Wharf  Machinery 206 

Cranes 206 

Telphers 210 

N.  Y.  Cargo  Hoists 211 

Motor  Trucks 213 

Conveyors 213 

Portable  Controllers      214 

Inclined  Truck  Elevators 215 

LOADING  AND  UNLOADING  SHIPS 215 

Cranes  vs.  Ship's  Gear       215 

Speed  Limiting  Points 221 

Reservoirs 222 

FREIGHT  HANDLING  ON  THE  WHARF 223 

Hand  Trucks 223 

Electric  Trucks 224 

Telphers 224 

Horse  Trucks 225 

Direct  Transfer  between  Cars  and  Ships      226 


APPENDIX 
COST   OF  WALLS,   PIERS,   SHEDS,   ETC. 

WALLS 229 

PIERS 237 

SHEDS 239 

MISCELLANEOUS 240 

INDEX  .                                                        243 


WHARVES  AND  PIERS 

CHAPTER  I 
INTRODUCTION 

DEFINITIONS 

THE  names  applied  to  various  kinds  of  wharves  and  their 
parts  are  loosely  used  and  vary  greatly  in  different  localities 
in  this  country. 

A  wharf  is  a  structure  at  which  vessels  may  land  and 
load  their  cargoes  and  passengers.  It  may  be  either  mar- 
ginal or  projecting,  but  in  most  localities  the  name  is  applied 
only  to  marginal  structures,  thus  distinguishing  them  from 
piers. 

A  pier  is  a  wharf  projecting  from  the  shore. 

A  quay  is  a  marginal  wharf.  The  name  is  common  in 
Europe,  but  is  used  scarcely  at  all  in  this  country. 

A  dock  is  an  artificial  basin  for  the  use  of  vessels.  Wet 
docks  are  those  in  which  the  vessels  remain  afloat  for  load- 
ing and  unloading.  They  are  the  prevailing  type  in  Europe, 
where  many  of  the  docks  are  excavated  from  the  land  on 
shores  of  narrow  rivers,  and  where  the  range  of  tide  is  very 
great.  They  are  usually  provided  with  gates  by  means 
of  which  the  water  is  maintained  at  a  constant  elevation, 
and  their  inconvenience,  in  that  vessels  can  enter  and 
leave  them  only  at  high  water,  is  obvious.  Dry  docks  are 
those  from  which  the  water  outside  is  excluded  by  means 
of  gates  and  from  which  the  water  inside  may  be  removed 
for  the  purpose  of  repairing  the  underwater  portions  of 
vessels.  They  sometimes  are  also  used  for  the  construe- 


2        ,      ,  WHARVES  AND  PIERS 

tion  of  ships.  The  word  ''dock"  is  improperly  applied  to 
piers  in  some  places  in  this  country,  notably  in  New  York, 
and  to  marginal  wharves  in  other  localities.  On  the 
Great  Lakes  and  adjacent  waters  the  word  usually  means 
a  retaining  structure  only. 

A  slip  is  the  space  between  two  adjacent  piers,  but  in 
some  places  such  spaces  are  called  docks. 

A  bulkhead  wall  is  a  name  given  in  New  York  City  to  a 
retaining  wall  for  a  marginal  wharf,  and  the  use  of  this 
name  has  spread  to  other  ports. 

A  dock  wall  or  quay  wall  is  a  marginal  wall  on  a  wharf 
or  pier. 

REQUIREMENTS  OF  A  WHARF 
The  requirements  of  a  wharf  are: 

1.  Sufficient  depth  of  water  for  the  vessels  which  are  to 
use  it.     This  is  usually  obtained  by  dredging  where  the 
natural    depth   is   not    sufficient.     In    some   places   where 
the  range  of  tide  is  very  great,  small  vessels  rest  on  the 
bottom  at  low  tide  or  on  shelves  constructed  alongside  the 
wharf  for  the  purpose. 

2.  Resistance  to  horizontal  forces  such  as  the  impact  of 
vessels,    currents,   floating  ice,   wind   and  waves,   and,   in 
the  case  of  retaining  walls,  to  the  thrust  of  the  earth  or, 
other  rilling. 

3.  Resistance  to  vertical  forces,  the  weight  of  the  struc- 
ture, and  of  the  live  loads  which  it  supports. 

4.  Resistance  to  decay,  abrasion,  and  the  teredo,  lim- 
noria,   and  other  destructive  marine  animals,   where  the 
latter  exist. 

5.  Elasticity   and   non-liability   to   injure   vessels   lying 
alongside.     This    is    particularly    important    in    exposed 
places  where  there  may  be  a  heavy  swell  or  waves. 

6.  Non-obstruction  to  the  free  flow  of  water,  ice.  and 
sewage  and  non-diminution  of  the  tidal  prism. 

7.  Non-obstruction  of  narrow  water-ways. 

8.  Economical  construction,   considering  first   cost  and 


INTRODUCTION  3 

total  cost  during  the  probable  commercial  life  of  the  struc- 
ture. 

9.   Rapidity  of  construction. 

10.  Security  against  destruction  by  fire. 

11.  Ease  in  making  repairs,   also  in  making  additions 
and  alterations  and  removals  due  to  increase  in  size  of 
vessels  and  changes  in  the  nature  of  the  freight  and  the 
methods  of  handling  it. 

12.  Compliance  in  all  navigable  waters  of  the  United 
States  with  the  regulations  of  the  Secretary  of  War. 

TYPES  .OF  WALLS 

Filled-in  piers  and  marginal  wharves  require  a  wall  of 
some  sort  to  retain  the  filling.  Retaining  walls  may  be 
divided  into  three  classes:  gravity  walls,  or  those  which 
depend  on  the  weight  of  the  structure  for  stability,  such  as 
are  shown  in  Figs.  10  and  19;  walls  with  relieving  platforms, 
illustrated  in  Figs.  44  and  57;  and  sheet-pile  walls,  held  in 
place  by  tie-rods  and  earth-anchors.  The  main  features 
of  all  three  types  may  be  combined  in  various  ways,  as  is 
shown  in  subsequent  chapters. 

TYPES  OF  PIERS 

There  are  three  types  of  piers  in  general  use.  The  pile- 
platform,  the  block-and-bridge,  and  the  solid-filled. 

The  pile-platform  type  is  perhaps  the  most  common. 
The  platform  may  be  of  wood,  steel,  or  concrete  and  may 
form  the  deck  of  the  pier  itself  or  may  be  located  at  about 
low-water  level  supporting  a  deck  on  posts,  as  in  Fig.  74 
or  a  filling  of  cinders  or  other  material  retained  in  place 
by  a  wall  around  the  edge  of  the  pier,  as  in  Fig.  73.  The 
piles  may  be  the  ordinary  timber  or  concrete  variety  or 
may  be  in  the  form  of  metal  or  concrete  columns  of  a 
diameter  varying  from  two  to  ten  feet  or  more. 

The  block-and-bridge  type,  as  its  name  implies,  consists 
of  blocks  usually  of  timber  crib  work,  but  in  some  cases  of 


4  WHARVES  AND  PIERS 

concrete   or   stone  masonry   resting   on   the   bottom   with 
bridges  extending  from  block  to  block. 

The  solid-filled  type  consists  of  a  retaining  wall  of  some 
kind  along  the  sides  and  outer  end  of  the  pier  with  the 
enclosed  area  filled  in  with  earth  or  other  material,  usually 
that  which  is  dredged  from  the  slips  alongside  the  pier. 
The  retaining  structure  may  be  at  the-  outer  edge  of  the 
pier,  as  in  Fig.  30,  or  it  may  be  located  inside  a  pile  plat- 
form, as  shown  in  Fig.  91. 

MATERIALS  OF  CONSTRUCTION 

Timber,  in  most  places  in  this  country,  is  at  the  present 
time  the  cheapest  material  for  the  construction  of  wharves, 
as  far  as  first  cost  is  concerned.  It  is,  however,  liable  to 
destruction  by  decay,  marine  animals,  and  fire. 

Air,  heat  and  moisture  are  necessary  for  the  decay  of 
wood.  If  wood  is  constantly  wet  and  deprived  of  air  by 
being  submerged  in  water  or  wet  earth  it  will  not  rot.  The 
necessary  heat  is  present  during  most  of  the  year  in  nearly 
all  places  where  wharves  and  piers  exist  and  decay  is  much 
more  rapid  in  tropical  climates  than  in  colder  regions. 
Where  wood  can  be  protected  from  waves,  rain,  snow,  and 
other  direct  sources  of  moisture,  the  moisture  from  the 
atmosphere  can  best  be  reduced  by  good  circulation  of  air. 
A  striking  example  of  decay  caused  by  insufficient  circula- 
tion of  air  is  found  in  the  piers  of  the  North  German  Lloyd 
Co.,  in  Hoboken,  opposite  New  York,  shown  in  Fig.  66. 
When  these  piers  were  built  they  were  surrounded  by  a 
tight  sheathing  of  six-inch  oak  plank  extending  from  low 
water  to  the  decks.  A  few  years  after  they  were  built  it 
was  found  that  the  caps  and  rangers  were  covered  with 
small  masses  of  fungus  and  were  in  danger  of  decaying. 
A  further  examination  showed  the  timber  to  be  saturated 
with  moisture  and  that  the  relative  humidity  of  the  air 
under  the  piers  approached  saturation  when  that  outside 
was  only  about  74%.  Enough  of  the  sheathing  was  re- 
moved to  give  a  free  circulation  of  air,  whereupon  the  timber 


INTRODUCTION  5 

dried  out  and  the  decay  has  not  progressed  since  to  any 
great  extent. 

The  elevation  below  which  timber  is  safe  from  rot  in 
fresh  water  like  the  Great  Lakes,  where  the  variation  of  the 
elevation  of  the  water  surface  is  slow  and  of  small  extent, 
is  about  one  foot  below  high  water.  In  most  tidal  harbors 
timber  remains  constantly  wet  up  to  about  half  tide  and  it 
is  usually  considered  that  timber  construction  below  these 
elevations  will  last  indefinitely  as  far  as  decay  is  concerned. 
Timber  below  a  plane  located  two  feet  above  mean  low  water 
is  considered  safe  from  rot  in  New  York,  where  the  mean 
range  of  tide  is  4.25  feet,  and  three  feet  in  Philadelphia, 
where  the  tidal  range  is  about  6  feet. 

In  the  rear  of  bulkhead  walls  in  tidal  waters  which  permit 
the  flow  of  water  through  them,  it  has  been  ascertained 
that  the  rise  and  fall  of  the  tide  is  retarded  and  the  time  of 
complete  submergence  is  increased  and  that  therefore  the 
elevation  at  which  timber  is  safe  from  decay  may  be  assumed 
at  a  higher  elevation  than  outside  such  walls. 

Timber  is  very  durable  where  it  can  be  protected  from 
rain  and  waves,  as  in  the  interior  portions  of  shedded  pile 
piers,  or  those  with  impervious  decks.  The  upper  portions 
of  piles  known  to  be  over  eighty  years  old  have  been  found 
in  perfect  condition  in  piers  in  New  York.  Careful  records 
extending  over  forty  years  have  been  kept  by  the  Depart- 
ment of  Docks  and  Ferries  in  that  city  and  show  that  in 
wooden  piers,  with  wooden  decks  covered  with  sheds,  such 
as  is  shown  in  Fig.  1,  the  life  and  cost  of  various  parts  are 
given  in  Table  I. 

The  percentage  of  average  annual  cost  as  given  in  this 
table  is  not  quite  correct,  in  that  the  cost  of  the  removal  of 


WHARVES  AND  PIERS 


TABLE  I 


Description  l 

Percentage  of 
total  original 
cost1 

Renewal 
required  l 

Percentage  of 
average  annual 
cost  of  renewal2 

Deck  sheathing 

12.0 

Every  6  yrs. 

2.00 

Backing  log 

1.8 

Every  8  yrs. 

0.23 

Fender    chocks,    in- 

cluding   vertical 

sheathing 

4.0 

Every  10  yrs. 

0.40 

Fender  piles 

4.7 

Every  12  yrs. 

0.40 

Decking 

11.3 

Every  15  yrs. 

0.75 

Bracing 

7.1 

50  %  in  every  20 

years 

0.18 

Rangers  and  caps 

24.4 

50  %  in  every  20 

years 

0.61 

Piles 

34.7 

33i%   in  every 

20  yrs.  above 

M.L.W.only 

0.58 

the  decayed  timber  has  not  been  included;  also,  in  regard 
to  the  last  item,  the  piles  decay  only  above  half  tide  and 
are  repaired  by  replacing  the  decayed  portion  by  new 
timber.  It  must  also  be  remembered  that  few  of  the 
interior  piles  of  a  shedded  pier  decay  to  any  great  extent, 
so  that  the  splicing  is  limited  largely  to  the  piles  on  the 
sides  and  end  of  the  pier,  and  the  weakening  of  the  structure 
due  to  the  splicing  is  not  very  great.  The  cost  of  splicing 
a  pile  is  from  $9  to  $12,  while  the  cost  of  a  new  70-foot  pile 
in  place  is  in  New  York  about  $16.50.  The  cost  of  removing 
an  old  pile  is  about  $3.50,  making  the  total  cost  of  entire 
renewal  approximately  $20.00.  Rangers  decay  first  on 
the  upper  surface  and  are  repaired  by  cutting  away  the 
decayed  portion  and  replacing  it  by  spiking  on  a  piece  of 
plank.  This  of  course  decreases  the  strength  to  some 
extent. 

The  durability  of  untreated  lumber  depends  largely  on 

1  C.  W.  Stamford  on  pier  construction  in  New  York  Harbor,  p.  515,  Trans. 
Am.  Soc.  C.  E.,  Vol.  LXXVII,  1914.  2  E.  G.  Walker,  ditto,  p.  523. 


INTRODUCTION  7 

the  amount  of  sap  wood  it  contains,  as  the  sap  wood  rots 
much  more  quickly  than  the  heart.  The  quality  of  yellow 
pine  lumber  has  been  deteriorating  and  the  price  for  material 


riJJSTu  J "  ^  J  fl.iLw 
.,  ..>  J  ./.>  Elevation, Outer  End  of  Her- 


Side  Elevation 


Fig.  1.     Wooden  Pier,  Dept.  of  Docks,  New  York,  N.  Y. 

with  a  restricted  amount  of  sap  wood  has  increased  greatly 
within  the  last  few  years.  The  opening  of  the  Panama 
Canal  has,  however,  brought  Douglas  fir  into  competition 
with  yellow  pine,  on  the  Atlantic  Coast.  This  lumber 
can  be  obtained  entirely  free  from  sap  wood  and  can  be 


8  WHARVES  AND  PIERS 

sold  profitably  at  much  less  than  the  price  recently  charged 
for  southern  long-leaf  yellow  pine  of  poorer  quality. 

It  is  very  desirable  that  the  energy  of  moving  vessels 
coming  in  contact  with  a  wharf  be  absorbed  by  the  elasticity 
of  the  structure  rather  than  by  its  destruction  or  by  the 
injury  of  the  vessel.  This  is  evident  when  we  consider 
that  a  ship  weighing  10,000  tons,  moving  at  a  rate  of  one 
mile  an  hour  or  about  1^  feet  a  second,  has  a  kinetic  energy 
of  about  350  foot  tons  and  for  double  this  velocity  the 
energy  is  nearly  1500  foot  tons  and  that  when  such  a  moving 
ship  comes  in  contact  with  a  wharf  this  amount  of  work 
must  be  expended  in  distorting  either  the  ship  or  the  wharf. 
It  is  stated  of  a  very  large  pier  of  concrete  pile  construction 
that  its  ability  to  withstand  blows  from  vessels  has  been 
demonstrated  and  that  in  every  case  the  plates  of  the 
steamers  were  the  sufferers.  The  owners  of  ships  will 
shun  such  a  pier  if  possible  and  will  use  in  preference  one 
which  is  elastic  and  will  not  injure  their  vessels.  Timber 
for  wharves  and  piers  has  advantages  over  steel,  stone,  or 
concrete  in  the  above  respect.  It  also  permits  of  greater 
rapidity  of  construction  and  more  easy  and  rapid  altera- 
tions, extensions,  or  removals. 

While  timber  wharves  and  piers  are  liable  to  destruction 
by  fire,  it  is  usually  the  freight  on  the  pier  which  starts  the 
fire  and  causes  the  greatest  portion  of  the  loss.  The  pier 
or  wharf  may,  by  using  only  timber  of  large  cross  section, 
be  of  the  slow-burning  type  of  construction  and  can  be  so 
designed  that  floating,  burning  materials,  such  as  cotton 
bales,  cannot  get  under  it  and  that  if  in  any  way  a  fire 
obtains  a  hold  under  the  deck  it  can  be  reached  by  the 
firemen  and  extinguished.  Many  instances  are  known  o 
fires  which  destroyed  the  shed  and  all  the  freight  on 
wooden  pier  but  did  not  burn  through  the  deck  or  injure 
the  substructure  in  any  way.  No  method  of  construction 
has  been  adopted,  however,  which  will  protect  a  Wooden 
pier  from  destruction  by  burning  oil  floating  on  the  water. 
Several  fires  of  this  nature  caused  by  the  rupture  of  sub- 


INTRODUCTION  9 

merged  oil  pipe-lines  or  of  oil  storage  tanks  near  the 
water  front  have  occurred,  and  have  usually  resulted  in  the 
destruction  of  all  wooden  piers  in  the  area  reached  by 
the  oil.  Piers  of  the  types  shown  in  Figs.  73,  74  and  75 
are  not  liable  to  this  danger. 

Timber  piles,  unless  creosoted,  are  uneconomical  in  water 
infested  by  marine  borers  except  for  temporary  structures. 
Partially  creosoted  piles  last  only  from  fifteen  to  thirty 
years,  as  they  are  subject  to  the  washing  out  of  the  preserva- 
tive and  to  the  decay  of  the  uncreosoted  interior,  and 
completely  impregnated  piles  usually  cost  nearly  as  much 
as  those  of  concrete.  In  many  cities,  however,  there  is 
enough  sewage  in  the  water  to  drive  away  the  destructive 
marine  animals,  and  in  such  places,  where  the  bottom  is 
suitable,  wooden  piles  are  cheaper  than  any  other  material 
for  the  foundations  of  piers  and  wharves;  at  any  rate,  for 
structures  the  commercial  life  of  which  will  probably  not 
exceed  forty  years. 

Wood  Preservatives.  —  Various  forms  of  coal  tar  products 
are  used  to  preserve  wood  in  wharves  and  piers  from  destruc- 
tion by  marine  borers  and  from  decay.  Wood  may  be 
treated  by  the  pressure  process,  in  which  the  material  is 
placed  in  a  closed  cylinder  and  after  being  treated  with 
steam  to  remove  the  sap  is  then  impregnated  with  the 
preservative  under  heavy  pressure;  by  dipping  in  a  tank 
containing  the  preservative;  and  by  applying  the  preserva- 
tive with  brushes.  All  methods  render  the  timber  most 
unpleasant  to  handle,  as  the  preservatives  are  all  irritating 
to  the  skin  and  eyes. 

Destructive  marine  animals  of  one  form  or  another 
thrive  in  nearly  all  salt  and  brackish  water  harbors  in  this 
country  and  to  the  south  of  it.  They  are  most  active  in 
warm  waters,  but  the  limnoria  is  so  plentiful  at  Halifax 
that  concrete  piles  from  75  to  90  feet  in  length  were  used 
in  building  steamship  piers  there,  and  Puget  Sound  is 
noted  for  the  size  and  abundance  of  its  teredos. 

Creosoted  piles  resist  the  action  of  these  animals  as  long 


10  WHARVES  AND  PIERS 

as  a  sufficient  amount  of  the  creosote  remains  in  the  wood, 
but  sooner  or  later  enough  of  the  preservative  washes  out 
and  the  borers  enter.  On  the  Pacific  Coast,  where  the 
teredo  is  very  active,  creosoted  piles  are  said  to  have  a  life 
of  one  year  for  each  pound  of  creosote  to  a  cubic  foot  of 
timber.  The  usual  practice  is  to  impregnate  the  piles  to 
a  depth  of  about  2  inches.  This,  however,  is  not  a  complete 
protection,  as  the  slightest  perforation  of  the  impregnated 
shell  results  in  the  entrance  of  the  teredo  and  the  destruc- 
tion of  the  interior  portion.  The  more  resinous  the  wood 
the  more  resistant  it  is  to  the  entrance  of  the  oil  of  creosote, 
and  cases  have  been  known  of  the  destruction  of  piles  by 
the  entrance  of  teredos  through  the  knots.  The  interior 
portion  sometimes  rots,  though  this  can  be  largely  pre- 
vented by  coating  the  tops  of  the  piles,  after  they  are  cut 
off,  with  some  form  of  preservative.  Complete  impregna- 
tion of  the  pile  is  extremely  expensive.  Some  kinds  of 
timber,  Douglas  fir  in  particular,  are  very  resistant  to  the 
entrance  of  creosote  into  the  pores.  It  is  extremely  diffi- 
cult to  obtain  uniform  penetration  and  in  a  creosoted  pile 
structure  some  of  the  piles  are  much  shorter  lived  than 
others.  The  permanence  of  the  preservative  and  the 
durability  of  the  wood  after  impregnation  depends  very 
largely  on  the  nature  and  quality  of  the  oil,  and  much  atten- 
tion is  at  present  being  given  to  the  study  of  this  point 
and  methods  to  ensure  uniformity  of  penetration. 

In  places  where  marine  borers  do  not  exist  and  where  the 
portion,  of  the  piles  above  low  water  is  the  only  part  which 
decays,  a  method  by  which  only  that  portion  of  the  pile 
could  be  impregnated  would  remove  all  the  objection  to 
wooden  piling  except  that  of  the  fire  risk.  Experiments 
are  being  made  with  some  promise  of  success  by  one  of  the 
manufacturers  of  wood  preservative  to  impregnate  the 
upper  portion  of  the  piles  for  a  distance  of  ten  feet  or  more 
by  lowering  a  cylinder  closed  at  the  top  over  the  pile  after 
it  has  been  driven  and  cut  off,  fitting  a  tight  collar  between 
the  lower  end  of  the  cylinder  and  the  pile  and  then  pumping 


INTRODUCTION  11 

the  preservative  into  the  cylinder  under  heavy  pressure. 
Attempts  have  been  made  to  obtain  the  same  object  by 
boring  a  vertical  hole  in  the  centre  of  the  pile  at  the  top 
and  filling  it  with  preservative.  This  method,  however, 
failed,  as  the  preservative  did  not  spread  radially  from 
the  hole,  but  ran  down  the  annual  rings  in  the  timber  and 
only  impregnated  a  core  about  the  size  of  the  hole. 

Decay  can  be  prevented  by  creosoting  by  the  pressure 
process,  though  some  examples  are  known  of  the  rotting 
out  of  the  interior  of  12-inch  square  timbers  preserved  by 
this  method.  Such  treatment  greatly  increases  the  cost 
of  the  lumber,  and  it  is  not  usually  considered  economical 
to  use  creosoted  material  for  wooden  wharves  except  in 
places  like  the  foundation  for  shed  posts,  where  it  cannot 
be  easily  renewed.  Treatment  by  the  dipping  process  is 
cheaper,  but  still  expensive  on  account  of  the  equipment  and 
handling  required,  and  is  open  to  the  same  objection  as  the 
pressure  process  in  that  the  cutting  of  the  lumber  after 
treatment  leaves  portions  of  the  material  exposed  to  decay. 

That  portion  of  a  wooden  wharf  which  is  subject  to 
rot,  decays  most  rapidly  at  the  points  where  moisture 
enters  and  does  not  dry  out,  such  as  at  butt  joints  and 
where  one  timber  bears  on  another.  A  brush  coating  of 
good  preservative  on  all  scarfs,  butts,  tenons,  tops  of  rangers 
and  stringers,  and  all  other  places  where  one  timber  rests 
on  or  against  another  and  on  all  timber  within  five  or  six 
feet  of  the  edge  of  a  wharf  or  pier  where  it  is  exposed  to 
spray  and  rain,  is  cheap,  greatly  increases  the  life  of  the 
timber,  and  makes  the  deterioration  more  uniform. 

One  advantage  of  treating  lumber  is  that  the  cheaper 
grades,  containing  a  large  amount  of  sap  wood  which, 
though  it  is  nearly  as  strong  as  the  heart,  decays  much 
more  rapidly,  can  be  made  as  durable  as  the  more  expen- 
sive grades. 

Concrete  enters  largely  into  the  construction  of  piers  and 
wharves.  It  has  the  advantage  over  wood  in  that  it  is 
not  subject  to  decay  or  destruction  by  fire  or  marine  borers. 


12  WHARVES  AND  PIERS 

Up  to  the  present  time  there  has  always  been  considerable 
uncertainty  as  to  the  durability  of  concrete  in  sea  water,  as 
there  have  been  many  failures  and  many  successes  and  the 
reasons  for  success  or  failure  have  not  in  all  cases  been 
ascertained.  The  present-day  knowledge  of  the  subject 
may  be  summed  up  as  follows. 

Well-made  concrete  which  is  constantly  submerged  in 
sea  water  and  which  has  not  been  exposed  to  the  washing 
action  of  water  currents  until  it  has  hardened  will  not 
disintegrate. 

Most  of  the  deterioration  of  concrete  in  sea  water  takes 
place  on  the  exposed  surface  between  high  and  low  water  in 
cold  climates  and  is  due  principally  to  frost  and  the  crystal- 
lization of  salts  and  in  less  degree  to  the  abrasion  of  floating 
timber  and  ice  and  to  the  action  of  waves.  Such  deteriora- 
tion may  be  easily  and  cheaply  repaired  by  means  of  the 
cement  gun  or  by  properly  secured  patching. 

Disintegration  can  be  largely  prevented  if  sufficient  care 
be  taken  in  the  selection  of  the  cement,  sand,  and  stone, 
in  the  mixing,  depositing,  the  construction  of  the  forms 
and  the  prevention  of  the  action  of  waves  or -currents  on 
the  concrete  before  it  is  hard.  The  cement  should  prefer- 
ably be  low  in  alumina,  and  the  sand  and  stone  should  be 
graded  in  size  so  as  to  give  the  densest  and  most  impervious 
mixture  possible,  in  order  to  prevent  the  entrance  of  the 
water  into  the  mass  and  the  consequent  disruptive  action 
of  the  frost  and  the  crystallization  of  the  salts  from  the 
sea  water.  This  impermeability  of  the  concrete  is  the 
most  important  element  of  durability  and  has  been  success- 
fully attained  by  the  use  of  a  large  proportion  of  cement. 
One  part  of  cement  to  one  and  one  half  parts  of  sand  have 
given  excellent  results,  while  those  with  one  part  of  cement 
to  two  parts  of  sand  and  more  appear  to  be  uncertain. 

Much  greater  reliability  can  be  obtained  by  moulding 
the  concrete  on  land,  as  is  the  case  in  concrete  piles  and  in 
the  great  blocks  of  the  New  York  bulkhead  wall,  than  by 
depositing  it  in  forms  below  high-water  mark,  where  it  is 


INTRODUCTION  13 

difficult  to  prevent  the  washing  action  of  the  water  before 
it  has  time  to  harden.  Concrete  deposited  under  water 
by  tremie  has  in  some  cases  been  successful,  but  the  diffi- 
culties in  obtaining  good  work  are  numerous  and  there  are 
so  many  examples  of  unsuccessful  results  following  the 
use  6f  this  method  that  it  is  generally  considered  undesirable. 

Concrete  Piles.  --  The  use  of  concrete  piles  and  columns 
has  made  great  strides  within  the  past  decade  for  situation 
where  great  permanency  is  desired  and  the  marine  borers 
render  the  use  of  timber  piles,  either  with  or  without  the 
use  of  preservative  treatment,  inadvisable.  This  applies 
particularly  to  piles.  Much  progress  has  been  made 
within  the  last  four  or  five  years  in  increasing  their  length 
and  in  reducing  the  cost  of  fabrication  and  handling.  Piles 
up  to  106  feet  in  length. have  been  used  where  hard  bottom 
was  at  great  depth  and  concrete  columns  have  been  placed 
extending  45  feet  below  low  water. 

The  reinforced  concrete  columns  mentioned  above  have 
been  used  to  a  considerable  extent  on  the  Pacific  Coast, 
where  they  originated.  They  consist  of  a  reinforced  con- 
crete cylinder  three  or  four  feet  in  diameter,  enlarged  at  the 
lower  end  to  give  a  bearing  of  great  area  on  hard  bottom 
or  a  group  of  wooden  piles. 

Concrete  piles  cost  from  three  to  four  times  as  much  as 
wooden  piles  of  the  same  length,  but  in  some  places  are 
cheaper  than  columns  of  concrete  resting  on  and  protecting 
clusters  of  wooden  piles.  They  are  somewhat  wasteful  of 
material,  as  the  strength  required  for  handling  them  with 
ordinary  appliances  is  greater  than  that  required  for  sup- 
porting the  load  after  the  pile  is  in  place.  They  will  support 
more  load  as  a  column  than  wooden  piles  in  certain  kinds 
of  bottom,  but  on  account  of  their  weight  will  not  support 
as  much  as  a  wooden  pile  where  skin  friction  is  relied  upon 
for  bearing  power. 

Concrete  sheet  piles  of  various  forms  with  and  without 
tongues  and  grooves  have  been  successfully  used  in  many 
places.  They  have  also  been  made  with  the  interlocking 


14  WHARVES  AND  PIERS 

portion  of  steel-sheet  piling  embedded  in  their  edges,  the 
cracks  between  the  adjacent  concrete  portions  of  the  piles 
being  filled  with  grout  to  protect  all  portions  of  the  steel 
from  rust.  Steel-sheet  piles  encased  in  concrete  are  also 
used,  but  are  comparatively  expensive. 

Stone  masonry  is  so  costly  that  it  enters  very  little  into 
the  construction  of  wharves  and  piers  at  the  present  time 
except  as  a  facing  of  walls  of  the  most  monumental  char- 
acter, such  as  the  New  York  bulkhead  wall,  and  for  pro- 
tective facing  for  concrete. 

Steel.  —  Steel  for  bearing  piles  and  sheet  piles  has  been 
used  to  some  extent,  the  latter  mostly  within  the  last  few 
years,  for  wharf  construction. 

Steel  piles  made  of  pipes  such  as  are  used  for  gas  and 
water  have  been  used  for  the  ocean  piers  at  Atlantic  City, 
N.  J.,  Old  Orchard,  Me.,  and  Coney  Island,  N.  Y.,  which 
were  built  twenty  or  thirty  years  ago.  These  piers  are 
subject  to  severe  wave  action,  and  those  at  Atlantic  City 
and  Old  Orchard  corroded  to  such  an  extent  in  about  ten 
years  that  they  had  to  be  rebuilt.  The  superstructures  of 
these  piers,  as  well  as  the  piles,  were  very  severely  attacked 
by  the  rust.  The  piles  of  one  of  the  piers  at  Coney  Island, 
however,  are  said  to  have  had  a  useful  life  of  about  twenty- 
five  years. 

Steel  sheet-piling  without  any  protection  except  paint 
has  been  used  for  retaining  walls  for  wharves  in  fresh  water, 
notably  in  Bremen;  at  the  entrance  to  the  United  States 
lock  at  Black  Rock,  Buffalo,  N.  Y.;  at  the  Barge  Canal 
Terminal  at  Rome,  N.  Y.;  at  Sandusky,  O.;  Hamilton 
and  Toronto,  Ont.;  Duluth,  Minn.;  and  in  salt  water  at 
Jacksonville,  Fla.  It  gives  a  very  simple  and  cheap  form 
of  construction  and  can  be  arranged  to  be  easily  replaced 
if  rusted  to  the  danger  point.  The  estimated  rate  of 
destruction  by  corrosion  is  so  low  that  it  is  claimed  that 
for  a  structure  having  an  assumed  commercial  life  of  thirty 
to  forty  years*  this  material  is  more  economical  than  wood 
or  concrete  in  fresh  water. 


INTRODUCTION  15 

The  rate  of  corrosion  in  water  of  the  commercial  steel  of 
the  present  day  is  very  uncertain  and  the  action  of  the 
various  factors  which  determine  it  are  at  present  not  entirely 
understood.  It  .is  known,  however,  that  corrosion  cannot 
take  place  without  oxygen  and  it  is  considered  that  steel 
buried  in  the  ground,  where  whatever  oxygen  there  is  in 
the  material  in  contact  with  the  steel  is  soon  exhausted, 
may  be  depended  on  to  last  indefinitely.  Where  steel  is 
subject  to  currents  or  waves  which  bring  fresh  supplies  of 
oxygen  to  the  metal  the  corrosion  is  much  more  rapid  than 
in  still  water.  On  the  other  hand  steel  in  salt  water  is 
often  covered  with  a  dense  growth  of  shell  fish  which  par- 
tially protects  it.  In  most  cases  the  corrosion  has  been 
found  much  greater  above  low- water  level  than  below  it. 
This  portion  of  a  pile,  exposed  to  alternate  wetting  and 
drying,  can,  like  the  sides  of  a  ship,  be  protected  by  paint- 
ing, but  the  expense  would  be  considerable.  In  most  cases  it 
has  not  been  attempted  and  in  others  it  has  failed  because 
the  waves  and  spray  washed  the  paint  off  before  it  had 
time  to  harden.  It  is  well  known  that  the  rate  of  corrosion 
is  much  greater  in  salt  than  in  fresh  water,  and  it  has  also 
been  ascertained  that  steel  bars  of  different  shapes  have 
different  rates  of  corrosion.  A  paper  by  B.  H.  Thwaite, 
an  English  engineer,  published  in  1880,  gives  as  the  result 
of  experiments  the  following  comparative  rates  for  the 
corrosion  of  steel: 

Foul  sea  water 1944 

Clear  sea  water .• 0970 

Foul  river  water 1133 

Pure  air  or  clear  river  water 0125 

Air  of  manufacturing  districts  or  sea  air 1252 

The   above   figures   are   the   " coefficients   of   corrosion" 

W 

to  be  used  in  the  formula  Y  =  ^rf>  where  Y  is  the  life  of 

C  Li 

the  metal  in  years,  W  the  weight  in  pounds  per  linear  foot 
of  steel  bar  exposed,  and  L  the  perimeter  of  the  steel  bar 
in  feet. 


16  WHARVES  AND  PIERS 

A  steel  plate  yV  inch  thick,  12  inches  wide,  has  a  weight 
of  17.85  pounds  per  linear  foot.  If  we  assume  that  only 
one  side  of  this  plate  is  exposed  to  sea  water,  the  perimeter 
so  exposed  would  be  one  foot.  Taking  the  highest  coefficient 
given  in  the  table  the  formula  for  the  life  of  the  plate  would 

17  85 

be     Y  =    in/f/i    TT  =  91  +  years.     A  steel-sheet  pile  with 
x  J- 


a  web  T7<r  inch  thick,  with  one  side  protected  by  filling, 
as  it  would  be  in  a  retaining  wall  or  a  tubular  pile  filled 
with  concrete,  might  be  expected  therefore  to  last  accord- 
ing to  the  formula  for  some  90  years  in  still  water  before 
the  tube  or  the  web  of  the  sheet  pile  is  entirely  destroyed. 
From  this  some  estimate  may  be  made  as  to  how  long 
such  piling  would  last  before  it  became  too  weak  to  bear 
the  stresses  imposed  on  it. 

The  wreck  of  the  U.S.S.  Maine  submerged  in  the  harbor 
of  Havana  for  thirteen  years  affords  considerable  informa- 
tion on  this  subject.  This  ship  was  built  of  modern  steel 
in  1895.  When  the  wreck  was  exposed  to  view  in  the  coffer- 
dam built  for  the  purpose  it  was  found  that  all  steel  which 
had  been  covered  with  mud  showed  only  a  thin  coating  of 
rust.  The  portions  which  were  totally  immersed  in  water 
were  only  slightly  corroded,  while  those  at  and  near  the 
surface  were  very  much  eaten  away.  Steel  in  contact  with 
or  in  proximity  to  brass  or  copper  was  destroyed  by  elec- 
trolytic action.  All  paint  below  the  water  surface  had 
totally  disappeared  and  all  submerged  metal  above  the 
mud  line  was  covered  with  a  dense  coating  of  shells  and 
other  marine  growths.  Havana  harbor  has  only  about 
18  inches  of  tide  and  almost  no  currents,  and  the  stillness 
of  the  water  and  the  coating  of  shells  probably  account, 
in  part,  for  the  remarkably  good  condition  of  the  steel. 

Cast  Iron.  —  Cast  iron  has  been  used  in  wharf  construc- 
tion in  the  form  of  columns  or  cylinders  in  many  places, 
and  while  expensive  in  first  cost  has  been  generally  success- 
ful. The  steamboat  pier  at  Old  Point  Comfort,  Va.,  was 


INTRODUCTION  17 

built  on  cast-iron  piles  one  inch  thick,  which  are  said  to  be 
in  good  condition  after  thirty-two  years  of  service,  though 
the  steel  superstructure  is  badly  corroded. 

Riprap,  or  "one  man  stone,"  if  it  can  be  obtained  cheaply, 
as  in  New  York,  where  the  price,  put  in  place  from  scows, 
varies  from  50^  to  70^  a  cubic  yard,  enters  largely  into  the 
construction  of  wharves  and  piers  and  has  a  decided  influence 
on  the  design. 

When  used  alone  as  a  retaining  structure  it  does  not 
afford  the  vertical  face  required  in  a  wharf,  but  when  com- 
bined with  masonry  walls,  sheet-piling,  or  platforms  it 
has  many  advantages.  It  is  also  used  to  stiffen  the  piles 
in  piers  and  marginal  wharves  where  the  water  is  more 
than  25  feet  deep,  also  to  consolidate  soft  mud,  to  distribute 
pressure  of  walls  on  soft  bottoms,  and  to  prevent  the  erosion 
of  earth  banks  by  waves  and  currents.  It  is  a  fact  not 
generally  known  that  piles  can  be  driven  through  freshly 
deposited  riprap  from  20  to  30  feet,  provided  that  the 
piles  are  properly  shod  and  that  the  fragments  of  stone  do 
not  exceed  16  inches  in  any  dimension. 

Concrete  vs.  Timber.  —  Concrete  and  timber  are  the 
materials  which  today  hold  the  first  places  in  wharf  con- 
struction. 

As  the  prices  for  piles,  lumber,  and  concrete  materials 
vary  greatly  according  to  locality,  the  relative  economy  of 
timber  and  concrete  can  only  be  determined  by  compara- 
tive designs  and  estimates  of  total  cost  for  the  commercial 
life  of  the  structure,  as  indicated  on  page  238.  As  the 
cost  of  such  designs  and  estimates  bears  only  a  small  ratio 
to  the  cost  of  a  large  wharf  or  pier,  it  is  well  worth  while 
to  work  out  a  number  of  them  for  each  case  and  if  possible 
obtain  actual  bids  on  them. 

Generally  speaking,  the  first  cost  of  concrete  is  greater 
than  that  of  timber  for  the  superstructure,  and  concrete 
piles  cost  two  or  three  times  as  much  as  those  of  creosoted 
timber  and  three  or  four  times  as  much  as  those  without 
preservative  treatment.  A  rough  comparison  of  the  cost 


18 


WHARVES  AND  PIERS 


of  timber  and  reinforced  concrete  of  the  same  volume  may 
be  obtained  from  Table  II. 

The  cost  of  the  piles  in  a  pier  usually  amounts  to  con- 
siderably more  than  fifty  per  cent  of  the  total  cost  of  the 
structure  and  in  this  item  may  be  found  one  of  the  greatest 
fields  for  ingenuity  and  originality  in  design.  Great  econ- 
omy may  be  obtained  by  the  use  of  a  combination  of  the 
two  materials,  in  which  the  portion  of  the  piles  subject  to 
decay  and  the  attacks  of  marine  borers  is  made  of  concrete 
and  the  portion  below  the  harbor  bottom  which  is  not 
subject  to  destruction  from  these  causes  is  of  timber.  Such 
combination  piles  have  been  used  in  a  number  of  cases, 
notably  at  San  Francisco  and  Bocas  del  Toro,  Panama,  as 
described  in  a  subsequent  chapter.  Wooden  piles  pro- 
tected with  a  coating  of  cement  mortar  have  been  success- 
fully used  at  Port  au  Prince,  Haiti,  and  at  San  Juan,  Porto 
Rico. 

TABLE  II 
COMPARISON  OF  COST  OF  EQUAL  VOLUMES  OF  CONCRETE  AND  LUMBER 


J  

JUfUUA  V  <MV«UV    1MM/«S    &VF4 

lumber  in  place  per 
1000  ft.  B.  M. 

cu.  yd. 

cu.  ft. 

$6.00 

$0.22 

$18.52 

7.00 

0.26 

21.61 

8.00 

0.30 

24.69 

9.00 

0.33 

27.78 

10.00 

0.37 

30.87 

11.00 

0.41 

33.95 

12.00 

0.44 

37.04 

13.00 

0.48 

40.12 

14.00 

0.52 

43.21 

15.00 

0.55 

46.29 

16.00 

0.59 

49.38 

17.00 

0.63 

52.47 

18.00 

0.67 

55.56 

19.00 

0.70 

58.64 

20.00 

0.74 

61.73 

CHAPTER  II 

PRIMARY  PRINCIPLES   OF  DESIGN 

COMMERCIAL  LIFE 

IN  the  economical  design  of  wharves  and  piers  an  esti- 
mate of  the  commercial  life  of  a  structure  is  of  the  first 
importance.  In  most  places  experience  has  shown  that 
traffic  shifts  from  place  to  place  and  that  localities  may 
become  obsolete  as  far  as  their  desirability  for  wharves 
and  piers  is  concerned.  Entire  industries  die  out  and  new 
ones  take  their  places,  and  new  methods  and  machinery 
are  adopted  for  handling  freight  and  for  construction  work, 
making  it  uneconomical  to  spend  money  for  great  perma- 
nence of  construction  where  permanence  of  usage  cannot 
be  definitely  foreseen. 

An  example  of  the  change  due  to  improved  mechanical 
devices  is  found  in  the  building  of  piers  on  the  North  River 
in  New  York  City.  The  earlier  piers  were  built  of  the 
crib-block  and  bridge  type  on  the  shores  of  the  East  River, 
where  there  was  a  suitable  bottom,  in  spite  of  the  swift 
currents.  These  piers  could  be  built  entirely  with  hand 
tools  and  did  not  require  any  pile  driving,  which,  with  the 
hand-power  drivers  of  those  days,  was  slow  and  expensive. 
With  the  development  of  the  steam-power  pile-driver  it 
became  possible  to  build  pile  piers  economically,  and  the 
North  River  front,  with  its  soft  bottom,  greater  width,  and 
slower  currents,  was  utilized. 

Another  example  showing  the  changes  due  to  the  size 
of  ships  and  shifting  of  trade  centres  is  found  in  the  Chelsea 
district  of  New  York.  About  1840  the  river  was  filled  in 
for  a  distance  of  1500  feet  out  from  the  shore.  Streets 


20  WHARVES  AND  PIERS 

were  laid  out  and  large  factories  built  on  the  land  thus 
made.  About  1880  a  demand  arose  for  longer  piers  for 
the  Atlantic  passenger  ships,  but  the  narrowing  of  the 
channel  by  the  lengthening  of  the  piers  was  forbidden  by 
the  United  States  authorities.  It  was  found,  however, 
that  at  the  prevailing  rates  of  rental  it  would  pay,  with 
the  use  of  modern  dredging  machinery,  to  remove  the 
filled-in  land  for  a  distance  of  500  feet  inshore,  together 
with  the  factories  and  other  buildings  and  to  construct 
piers  800  feet  long.  This  was  actually  done  and  the  im- 
provement completed  in  1909,  about  seventy  years  after 
the  land  was  originally  filled.  In  the  Brooklyn  Navy 
Yard  a  large  artificial  island  was  built  and  partially  re- 
moved and  replaced  with  piers  within  half  a  century. 
Numerous  other  examples  of  changes  in  less  than  fifty 
years  might  be  quoted,  particularly  in  Europe. 

These  and  similar  experiences  have  led  the  engineers  of 
the  New  York  Dock  Department  to  consider  that  it  is  not 
profitable  to  spend  money  for  permanence  of  piers  in  excess 
of  that  required  to  give  them  a  life  of  about  forty  years. 
In  designing  a  state-owned  pier,  recently  built,  only  twenty- 
five  years  have  been  allowed  as  the  commercial  life  of  the 
structure.  In  another  city,  on  the  other  hand,  estimates 
of  the  economy  of  methods  of  construction  ensuring  great 
durability  have  been  based  on  a  life  of  one  hundred  years. 
The  fallacy  of  basing  a  comparison  of  the  economy  of 
permanent  and  semipermanent  types  on  an  assumed  com- 
mercial life  of  one  hundred  years  is  shown  by  the  rarity  of 
wharves  that  have  been  in  use  for  such  a  length  of  time 
without  outliving  their  economic  usefulness. 

Comparative  Estimates  of  Cost.  —  Having  decided  on 
the  number  of  years  to  be  allowed  as  commercial  life  of  a 
proposed  wharf,  in  order  to  determine  the  relative  economy 
of  various  designs  involving  variations  of  cost  and  dura- 
bility, the  total  cost  of  the  proposed  structure  together 
with  the  cost  of  borrowing  the  money  for  building  it  should 
be  estimated.  Such  an  estimate  should  include  as  many 


PRIMARY  PRINCIPLES  OF  DESIGN  21 

of  the  following  items  as  may  apply  in  each  individual 
case: 

1.  First  cost  of  the  structure  or  equivalent  sinking  fund 
charges. 

2.  Interest  on  the  first  cost. 

3.  Charge   for   physical   depreciation   involving   loss   of 
earning  power. 

4.  Charge    for    obsolescence    involving   loss    of    earning 
power. 

5.  Fire  insurance. 

6.  Insurance  against  loss  of  income  from  fire. 

7.  Loss  of  income  during  repairs,  renewals,  or  alterations. 

8.  Annual  average  charge  for  repairs  or  charge  at  stated 
periods. 

9.  Operating  expenses. 

All  these  items  except  the  first  may  be  estimated  on  the 
annual  average.  If  this  is  done  all  except  the  first  should 
be  treated  as  annuities  and  their  total  cost  should  be  cal- 
culated as  that  of  the  sum  of  annual  instalments  plus  the 
compound  interest  on  them.  This  is  given  by  the  formula 


in  which  A  is  the  annual  instalment,  r  the  rate  of  interest, 
and  n  the  life  of  the  structure  in  years.  An  annual  average 
for  repairs  and  depreciation  may  in  some  cases  be  replaced 
by  percentages  of  the  cost  of  various  parts  of  the  structure 
at  the  end  of  stated  terms,  as  indicated  in  Table  I.  In 
such  cases  they  should  be  treated  as  investments  at  com- 
pound interest  for  the  remainder  of  the  life  of  the  structure. 

The  items  for  insurance  against  loss  of  income  from  fire 
and  for  interruptions  of  income  during  repairs  or  renewals 
are  somewhat  unusual,  but  they  may  easily,  under  some 
arrangements  of  rental,  be  of  great  importance. 

If  the  life  of  the  bonds  is  greater  than  the  estimated  life 
of  the  structure,  then  the  sinking  fund  must  be  such  as  to 
produce  a  sum  at  the  termination  of  the  life  of  the  structure 


22  WHARVES  AND  PIERS 

which,  if  invested  in  other  securities,  will  pay  off  the  bonds 
when  they  are  due. 

Of  course  when  capitai  is  limited  it  is  not  always  possible 
to  utilize  the  most  economical  design,  as  outlined  above, 
and  the  question  is  changed  from  how  to  build  the  most 
economical  wharf,  to  how  to  build  the  most  economical 
wharf  of  the  required  size  for  the  amount  of  money  available. 

GROWTH  OF  SHIPS 

Another  most  important  consideration  in  designing  is 
the  probable  growth  of  ships.  Not  only  have  the  At- 
lantic passenger  and  freight  liners  grown  from  the  425-foot 
Scythia  of  1874  to  the  Aquitania  and  Vaterland  of  the 
present  day,  with  a  length  of  over  900  feet  and  a 
draught  of  35  feet,  but  the  size  of  all  vessels  has  increased 
wherever  the  depth  and  width  of  channels  in  harbors  and 
canals  has  permitted.  That  this  applies  not  only  to  the 
great  passenger  ships  but  to  the  ordinary  freighter  as  well 
is  shown  by  the  statistics  of  the  Suez  Canal.  In  1875  the 
average  gross  tonnage  of  the  vessels  passing  through  it 
was  1969,  in  1900  it  was  3981,  and  in  1911  it  had  increased 
to  5115.  These  increases  followed  the  increase  of  the 
depth  of  the  canal,  which  previous  to  1890  allowed  the  use 
of  vessels  drawing  24  feet  7  inches,  from  1890  to  1902,  25 
feet  7  inches,  from  1902  to  1906,  26  feet  3  inches,  in  1906, 
27  feet,  in  1908,  28  feet.  In  1915  it  was  expected  that  31 
to  32  feet  draught  would  be  allowed.  While  there  will  always 
be  many  ships  of  small  size  and  draught,  built  to  go  into 
the  more  remote  and  less  important  harbors,  it  is  usually 
the  rule  that  the  larger  the  ship  the  lower  is  the  cost  of 
transportation  and  in  consequence  channels  are  artificially 
deepened,  canal  locks  enlarged,  and  a  demand  created  for 
increase  in  the  length  and  width  of  wharves  and  piers  and 
in  the  depth  of  water  alongside  them. 


PRIMARY  PRINCIPLES  OF  DESIGN  23 

MARGINAL  WHARVES  vs.  PIERS 

In  making  the  design  for  a  general  plan  for  the  develop- 
ment of  water-front  property  the  question  as  to  whether  the 
wharves  shall  be  of  the  marginal  or  projecting  type  is 
usually  determined  by  the  local  conditions.  Marginal 
wharves  are  required  in  narrow  rivers  or  in  those  in  which 
the  velocity  of  the  current  is  excessive.  For  a  given  length 
of  water  front,  however,  piers  placed  at  right  angles  to  the 
shore  line  give  greater  length  of  wharfage  room  in  relation 
to  the  length  of  the  water  front  than  any  other  arrange- 
ment. For  example,  a  marginal  wharf  2000  feet  long  will 
accommodate  only  four  500-foot  ships,  but  on  such  a  prop- 
erty may  be  built  five  piers,  each  1000  feet  long  and  150 
feet  wide  with  slips  250  feet  wide  between  them  which 
would  provide  berthing  space  for  twenty  ships.  Where 
the  water-front  property  has  a  high  value  per  linear  foot 
the  economy  of  the  latter  arrangement  is  evident. 

Where  there  is  not  sufficient  distance  between  the  shore 
line  and  the  line  limiting  the  distance  to  which  piers  are 
permitted  to  extend,  for  piers  of  the  required  length  to  be 
placed  at  right  angles  with  the  shore,  they  may  be  placed 
at  an  acute  angle  with  it.  While  this  arrangement  gives 
longer  piers  inside  a  given  pierhead  line,  and  makes  it 
easier  for  vessels  to  enter  and  leave  the  slips,  especially  in 
narrow  waterways  and  swift  currents,  it  allows  of  less 
useful  wharfage  room  per  foot  of  water  front  for  piers  of  a 
given  width,  increases  the  cost  of  the  piers  on  account  of 
the  angular  construction,  and  wastes  deck  space. 

Under  certain  conditions  it  is  desirable  to  place  a  mar- 
ginal wharf  at  a  distance  from  the  shore.  Such  structures 
may  be  shaped  like  the  letter  T  or  may  be  joined  to  the 
shore  at  one  end.  The  T  wharf  of  the  Quartermaster's 
Department  at  Governor's  Island,  New  York  Harbor,  is  a 
good  example.  In  this  case  there  was  a  masonry  sea-wall 
already  built,  and  as  there  was  no  occupancy  of  the  water- 
front property  there  was  no  reason  for  economizing  on  the 


24  WHARVES  AND  PIERS 

length  of  water  front  required  for  the  pier.  A  filled-in 
marginal  wharf  extending  to  water  of  sufficient  depth  would 
have  obstructed  the  swift  tidal  currents.  A  pier  at  right 
angles  to  the  shore  would  have  required  expensive  dredging 
in  the  hard  bottom  or,  if  of  sufficient  length  without  dredg- 
ing, would  have  extended  into  very  deep  water  and  would 
have  obstructed  the  very  congested  waterway.  The  prob- 
lem was  solved  by  building  a  pile  wharf  parallel  to  the  shore 
at  a  point  where  the  water  was  sufficiently  deep  and  con- 
nected to  the  shore  at  the  middle  by  a  roadway  of  similar 
construction. 


DIMENSIONS  OF  WHARVES 

The  length  of  a  pier  is  usually  determined  by  the  nature 
of  the  vessels  it  is  designed  to  accommodate  and  the  local 
conditions,  such  as  the  pierhead  and  bulkhead  lines  es- 
tablished in  all  harbors  under  improvement  by  the  federal 
government. 

The  width  of  a  wharf  should  be  sufficient  to  allow  for  the 
economical  distribution  and  collection,  the  sorting,  in- 
spection, and  temporary  storage  of  the  freight.  The  eco- 
nomical width  is  also  affected  by  the  front-foot  value  of 
the  property  on  which  the  wharf  is  located. 

In  order  that  the  time  required  to  load  and  unload  a 
vessel  may  be  reduced  as  much  as  possible,  the  wharf 
area  to  be  provided  for  each  vessel  berthed  at  the  wharf 
is  that  necessary  for  the  storage  of  an  entire  inbound  and 
outbound  cargo  less  the  amount  of  cargo  that  can  be  brought 
to  and  taken  from  the  wharf  while  the  vessel  is  loading  and 
unloading  and  less  the  amount  that  can  be  transferred 
directly  between  the  vessel  and  cars  and  lighters. 

The  freight-holding  capacity  of  a  given  area  varies  in 
proportion  to  the  depth  to  which  the  freight  is  piled,  and 
the  area  required  to  afford  a  given  capacity  would  be 
greatly  affected  by  the  presence  or  absence  of  tiering 
machines  or  overhead  travelling  hoists. 


PRIMARY  PRINCIPLES  OF  DESIGN  25 

As  the  rate  at  which  freight  can  be  transferred  between 
the  wharf  and  the  ship  does  not  vary  in  proportion  to  the 
capacity  of  the  vessel,  it  usually  follows  that  the  smaller 
the  ship  the  nearer  the  minimum  wharf  area  required 
approaches  that  required  for  storing  an  entire  inbound 
and  outbound  cargo. 

The  cost  of  collecting  and  distributing  freight  on  the 
wharf  depends  largely  on  the  horizontal  distance  it  has  to 
be  transported,  and  it  is  evident  that  in  order  to  reduce 
this  distance  to  a  minimum  the  width  of  the  wharf  should 
be  such  that  the  area  provided  for  each  vessel  should  be 
located  abreast  of  the  vessel  and  for  a  short  distance  ahead 
and  astern. 

A  width  of  from  80  to  150  feet  has  usually  been  con- 
sidered sufficient  for  ordinary  steamship  service,  but  both 
in  foreign  and  domestic  ports  the  tendency  is  to  provide 
greater  width,  and  piers  up  to  400  feet  in  width  have  been 
built,  for  large  vessels,  in  this  country.  An  example  is 
shown  in  Fig.  71. 

It  is  stated  that  the  present  practice  in  Hamburg  is  to 
provide  a  shed  200  feet  wide  for  each  ship.  For  a  pier  this 
would  require  400  feet  of  width  of  shed  in  addition  to  road- 
ways and  railroad  tracks. 

The  width  of  the  slips  between  piers  should  be  sufficient 
to  provide  for  fenders  on  the  piers,  for  ships  lying  at  the 
piers,  for  lighters  lying  between  the  ships,  and,  in  places 
where  it  is  required  that  large  passenger  ships  be  coaled  at 
a  rapid  rate,  for  coal  barges  to  lie  between  the  ships  and 
the  piers.  The  tendency  to  make  the  slips  too  narrow  in 
order  to  increase  the  number  of  piers  on  a  given  length  of 
water  front  has  been  the  cause  of  much  congestion  in  places 
where  the  use  of  lighters  is  common. 

The  elevation  of  the  decks  above  mean  high  water  should 
be  sufficient  for  them  to  be  free  from  danger  of  flooding  by 
waves  at  extreme  high  tide,  and  should  not  be  so  great  as 
to  interfere  with  the  handling  of  cargo  at  low  tide.  In 
ordinary  sheltered  harbors  the  height  is  usually  from  5 


26  WHARVES  AND  PIERS 

to  6  feet  above  high-water  level.  In  New  York,  where  the 
mean  range  of  tide  is  4.25  feet  and  extreme  tides  have  risen 
to  4  feet  above  mean  high  water,  the  decks  of  nearly  all 
piers  and  wharves  have  been  placed  5  feet  above  the  latter 
elevation  for  half  a  century  or  more  and  there  is  no  tendency 
to  make  any  change.  In  Boston,  at  the  Commonwealth 
piers,  where  the  mean  range  of  tide  is  about  ten  feet,  the 
decks  are  8  feet  above  mean  high  water.  At  Halifax,  on 
concrete  pier  No.  2,  with  6  feet  of  tide  the  deck  is  13  feet 
2  inches  and  the  railroad  tracks  on  the  pier  9  feet  8  inches 
above  high  water.  In  Philadelphia,  with  6  feet  of  tide, 
the  decks  on  the  Municipal  Wharves  are  6  feet  above  mean 
high  water.  In  Havana  two  double-deck  steamship  piers 
have  the  lower  deck  at  5  feet  8  inches  and  the  upper 
deck  at  29  feet  above  mean  low  water,  but  the  maximum 
variation  of  the  water  level  is  only  18  inches. 

LIVE  LOADS 

The  live  load  to  be  provided  for  in  designing  wharves 
varies  from  75  pounds  per  square  foot  for  those  designed 
for  handling  passengers  only,  to  1000  pounds  for  heavy 
freight.  It  is  difficult  to  prevent  overloading  by  such 
heavy  materials  as  pig  lead  or  materials  which  are  easily 
piled  to  a  great  height,  such  as  sugar  in  bags,  tin  sheets  in 
boxes,  or  sand  and  broken  stone.  Many  wharves  have 
failed  from  overloading,  especially  where  they  have  deterio- 
rated from  age  and  decay.  A  heavy  live  load  should  be 
provided  for  rather  than  a  light  one. 

Table  III  shows  the  live  loads  provided  for  by  several 
important  wharves. 

TIDAL  PRISM 

One  of  the  requirements  of  all  wharf  construction  in 
tidal  harbors  is  that  it  shall  not  diminish  what  is  known 
as  the  tidal  prism.  This  is  defined  as  that  body  of  water 
between  mean  high  and  mean  low  water  levels,  which 
enters  and  leaves  a  harbor  with  each  tide.  It  is  relied  on 


PHI  MARY  PRINCIPLES  OF  DESIGN 


27 


TABLE  III 


Live  load  —  Ibs.  per  square  foot 

Lower  deck 

Upper  deck 

N.  Y.  Dock  Dept.  Piers 

500 

350 

N.  Y.  Dock  Dept.  Bkhd.  Wall 

1000 

Havana  Steamship  Docks 

250 

400 

Halifax  —  Concrete  Pile  Pier  No.  2 

1000 

500 

Philadelphia  —  Municipal  Wharves 

600 

300  and  400 

San  Francisco  —  State  Piers 

500 

Baltimore  —  Municipal  Wharves 

600 

Tampico  —  Oil  Dock 

800 

in  many  places  to  scour  and  maintain  the  channels  in  the 
harbors  and  those  across  the  bars  at  their  entrances.  Any 
diminution  of  this  prism  tends  to  make  the  channels 
shallower  and  adds  to  the  expense  of  maintaining  their 
required  depth  by  dredging.  This  is  taken  into  considera- 
tion by  the  federal  authorities  in  fixing  the  bulkhead  line 
or  outshore  limit  for  solid  filling  which,  together  with  the 
pierhead  line  or  outshore  limit  of  structures  of  any  kind, 
is  established  in  all  harbors  under  the  jurisdiction  of  the 
Secretary  of  War,  where  it  is  required  by  the  local  condi- 
tions. 


CHAPTER   III 
DETAILS   OF  TIMBER   CONSTRUCTION 

PILES  AND  PILE  DRIVING 

PILES  up  to  60  feet  in  length  are  easily  obtained  on  the 
Atlantic  Coast,  of  spruce,  white  pine,  oak,  Norway  pine,  or 
short-leaf  pine,  the  latter  material  supplying  the  bulk  of 
the  demand.  Piles  of  60  to  85  feet  in  length  are  usually  of 
long-leaf  pine;  they  are  somewhat  difficult  to  obtain  and 
are  rapidly  increasing  in  price;  piles  over  85  feet  in  length 
are  not  generally  on  the  market,  and  where  longer  piles  are 
required  splicing  is  usually  resorted  to.  Spruce  piles  are 
not  as  durable  above  water  as  those  of  the  various  species 
of  pine;  oak  piles  are  more  expensive  than  those  of  other 
woods  and  are  used  principally  for  fender  piles  or  in  places 
where  the  driving  is  especially  difficult;  some  cypress  piles 
are  also  used.  Piles  of  Douglas  fir  up  to  120  feet  long,  of 
perfect  form,  are  readily  obtained  on  the  Pacific  Coast 
and  the  promise  of  delivery  on  the  Atlantic  Coast  by  way 
of  the  Panama  Canal  of  fir  piles  up  to  110  feet  long,  which 
is  the  limit  that  can  be  carried  on  the  decks  of  vessels  en- 
gaged in  the  lumber  trade  at  reasonable  prices,  will  probably 
soon  be  fulfilled. 

Pile  Formulas.  -  -  The  impossibility  of  the  universal 
application  of  the  ordinary  formulas  for  the  bearing  power 
of  piles  has  been  demonstrated  again  and  again  in  the  deep 
mud  and  in  some  hard  bottoms  in  New  York  Harbor.  Long 
piles  which  do  not  reach  hard  bottom  in  the  uniform  silt 
of  the  Hudson  River,  which  under  the  Engineering  News 
formula  are  safe  for  only  4j  tons,  are  designed  for  a  safe 
load  of  12  tons.  In  similar  material  piles  have  been  found 


TIMBER  CONSTRUCTION  29 

capable  a  few  days  after  being  driven  of  supporting  35 
tons  without  detrimental  settlement. 

Steam  vs.  Drop  Hammers.  —  It  is  a  curious  fact  that,  in 
spite  of  the  known  advantages  of  the  steam  pile  hammer 
over  the  drop  hammer  the  former  is  not  in  general  use  by 
contractors  engaged  in  water-front  construction  in  New 
York  and  many  other  Atlantic  ports.  The  reason  for  this 
is  not  apparent.  The  steam  hammers  have  been  tried  by 
many  contractors,  but  their  advantages,  for  floating  pile 
drivers  at  any  rate,  have  not  been  great  enough  to  offset 
the  increased  first  cost  of  the  equipment  and  gain  for  tjiem 
the  general  use  they  have  attained  in  work  other  than 
wharf  building. 

Lagged  Piles.  —  Where  the  mud  is  very  deep  and  de- 
ficient in  supporting  power  the  skin  friction  of  the  piles 
may  be  increased  by  lagging  the  piles  with  four  wooden 
strips  5  inches  by  6  inches  in  section,  fastened  on  with  screw 
bolts  and  spikes.  The  efficiency  of  this  device  has  been 
questioned  by  some,  but  the  experiments  of  the  New  York 
Dock  Department  are  conclusively  in  its  favor  and  it  has 
been  used  in  many  important  piers  in  New  York. 

Foalting  Drivers.  —  Floating  pile  drivers  in  which  leads 
similar  to  those  in  use  on  land  are  mounted  on  scows  are 
generally  used  for  wharf  construction.  Besides  their  special 
function,  they  are  of  great  general  usefulness.  Equipped 
with  a  cable  on  which  is  placed  a  trolley,  from  the  top  of 
the  ways  to  some  convenient  point,  they  are  used  for  "  tele- 
graphing" or  transferring  piles  and  timber.  A  boom  with 
its  lower  end  fitted  to  a  socket  in  a  drop  hammer  converts 
the  pile-driver  into  a  fairly  efficient  derrick  boat.  Many 
floating  pile-drivers  are  equipped  with  air  compressors  for 
operating  wood-boring  tools  and  with  powerful  pumps  for 
jetting  down  piles.  Special  engines,  differing  from  the 
ordinary  machine  for  use  on  land,  in  that  they  are  equipped 
with  two  or  more  pair  of  extra  winch  heads,  are  essential 
for  manoeuvring  the  scow  and  the  rapid  and  efficient 
handling  of  the  piles. 


30  WHARVES  AND  PIERS 

Piles  are  removed  with  floating  equipment  by  pulling 
with  heavy  wire-rope  purchases.  When  these  are  attached 
to  the  heads  of  the  leads  they  bring  very  severe  stresses  on 
them  and  unless  the  latter  are  very  strong  they  will  be 
bowed  out  by  continued  service  of  this  kind.  In  Boston 
large  derrick  scows  or  lighters  are  used  for  pulling  piles,  a 
heavy  gallows  frame  being  mounted  on  the  end  opposite 
to  the  engine  and  derrick.  The  derrick  is  used  for  placing 
the  piles  on  the  deck  of  the  lighter  for  transportation.  In 
other  places  so-called  "catamarans"  are  used  for  the 
transportation  of  piles.  These  are  rafts  of  old  white  pine 
timber  with  strong  posts  at  the  corners  and  along  the  sides 
for  holding  the  cargo  of  piles  in  place. 

Inclined  Drivers.  —  -  There  are  several  forms  of  machines 
and  attachments  for  driving  bracing  or  batter  piles.  The 
best  floating  pile  drivers  for  this  purpose  are  built  with  a 
well  into  which  the  rear  ends  of  the  sills  of  the  leads  are 
lowered,  the  forward  end  of  the  sills  being  connected  to 
the  hull  by  hinges.  Other  machines  are  fitted  so  that 
the  rear  ends  of  the  sills  may  be  raised  and  the  ways  in- 
clined forward.  The  bow  of  the  scow  in  machines  so 
equipped  is  inclined  instead  of  vertical,  as  is  customary  in 
most  floating  drivers.  This  form  has  the  great  disad- 
vantage that  bracing  piles  inclining  inward  from  the  edge 
of  the  deck  of  a  pier  must  be  driven  before  the  vertical 
piles.  An  unusual  form  is  that  in  which  an  independent 
set  of  hammer  ways  or  guides  is  hung  on  a  pivot  at  the 
top  of  the  tower  and  is  inclined  from  the  vertical  by  moving 
the  lower  end  out  to  either  side  as  required.  The  most 
common  arrangement,  however,  is  an  independent  set  of 
short  inclined  leads  lashed  to  the  ordinary  standing  leads 
in  a  plane  at  right  angles  to  them.  This  is  a  cheap  rig  and 
is  fairly  efficient  for  occasional  work  where  the  piles  are 
not  too  long  and  the  driving  not  very  difficult. 

For  inclined  piles  in  the  interior  of  a  pier  a  land  machine 
with  leads  inclined  forward  from  the  engine  and  boiler  has 
been  used. 


TIMBER  CONSTRUCTION  31 

Pile  Followers.  —  Where  piles  are  to  be  cut  off  at  some 
distance  below  low  water  they  are  sometimes  driven  with 
a  follower  consisting  of  a  piece  of  timber  or  a  steel  tube 
joined  to  the  head  of  the  pile  by  means  of  a  sleeve.  This 
method  does  not  usually  produce  very  good  results  unless 
the  followers  are  carefully  and  very  strongly  and  expensively 
made.  The  side  strains  during  driving  are  very  great  and 
the  usual  home-made  rig  is  defective  in  size  and  strength 
and  results  in  frequent  break-downs  and  unsatisfactory 
inclination  and  unevenness  of  spacing  of  the  piles.  This 
method  is  also  apt  to  broom  the  heads  of  the  piles  to  such 
an  extent  as  to  make  it  necessary  to  cut  them  off  in  order 
to  properly  support  concrete  or  other  materials.  In  places 
where  the  tides  are  not  excessive  and  plane  of  cut-off  not 
too  far  below  low  water  it  is  often  cheaper  to  dispense  with 
the  follower  and  waste  a  portion  of  the  pile. 

Leads  which  can  be  extended  below  the  surface  of  the 
water  to  guide  the  follower  are  sometimes  used  and  produce 
better  results  than  when  the  follower  is  used  without  them. 
A  steel  tube,  of  sufficient  diameter  to  contain  the  pile 
without  binding,  driven  a  short  distance  into  the  bottom, 
has  also  been  successfully  used  for  guiding  the  follower. 

LATERAL  SUPPORT  FOR  PILEH 

Where  the  depth  of  water  does  not  exceed  about  25  feet 
the  bearing  power  of  ordinary  wooden  piling  of  14  to  16 
inches  diameter  when  considered  as  a  column  is  usually 
sufficient  for  loads  of  from  24,000  to  30,000  pounds,  but  in 
cases  where  the  water  is  deeper  the  piles  need  additional 
support,  both  for  strength  as  a  column  and  for  stiffness  to 
resist  lateral  forces,  such  as  currents  and  the  impact  of 
vessels  and  ice.  Under  such  conditions  banks  of  riprap  or 
broken  stone,  the  pieces  of  which  do  not  measure  more 
than  16  inches  in  any  dimension,  and  round  cobble-stone 
not  exceeding  six  inches  in  any  dimension,  are  used  for 
giving  the  necessary  support.  The  latter  material  offers 
less  resistance  to  pile-driving. 


32  WHARVES  AND  PIERS 

The  bed  of  stone  may  be  put  in  place  before  or  after  the 
piles  are  driven.  In  very  deep  mud  where  the  piles  do  not 
reach  to  hard  bottom  the  stone  usually  settles  and  carries 
the  piles  with  it.  If  the  stone  is  placed  after  the  piles  are 
driven  it  has  a  tendency  to  arch  between  the  piles  and 
increase  the  load  on  them.  In  such  cases  it  is  necessary 
to  provide  some  means  of  bringing  the  structure  up  to 
grade  after  the  settlement  has  taken  place. 

Where  the  piles  reach  to  hard  bottom  through  a  layer  of 
soft  mud  the  stiffening  material  should  be  deposited  before 
the  piles  are  driven  or  if  this  is  not  done  great  care  must 
be  taken  in  placing  it  in  order  that  the  movement  of  the 
mud  may  not  break  or  displace  the  piles.  A  large  pile 
pier  in  Baltimore  was  built  on  this  kind  of  a  bottom  and 
after  the  shed  had  been  built  it  was  decided  to  place  gravel 
around  the  piles  to  give  them  additional  support.  Holes 
were  cut  in  the  deck  for  this  purpose,  and  when  the  gravel 
was  deposited  the  weight  of  the  gravel  caused  the  mud  to 
flow  laterally  from  between  it  and  the  hard  bottom.  It 
was  expected  that  the  movement  would  be  equal  on  both 
sides  of  the  pier,  but  it  was  so  much  greater  to  one  side 
than  to  the  other  that  the  mud  caused  the  piles  to  tip  over 
till  they  could  not  carry  their  load.  The  result  was  the 
entire  destruction  of  a  large  portion  of  the  pier  and  shed, 
the  destroyed  area  containing  about  5000  piles. 

The  lateral  support  of  soft  mud  and  silt  is  much  greater 
than  might  be  expected,  but  the  extent  to  which  this  support 
may  be  relied  on  cannot  be  calculated  and  is  a  matter  to  be 
decided  by  judgment  based  on  local  history  and  experience. 

TEST  PILES  AND  BORINGS 

Thorough  examination  of  the  bottom  by  means  of  wash 
borings  as  well  as  test  piles  and  a  careful  study  of  the  geo- 
logical formation  is  necessary  in  most  cases.  Test  piles  are 
unreliable  where  dredging  is  to  be  done  unless  driven  after 
the  dredging.  A  case  occurred  in  New  York  where  test 
piles  and  wash  borings  were  driven  to  determine  the  length 


TIMBER   CONSTRUCTION  33 

of  'piles  for  a  large  pier  located  on  a  bottom  consisting  of 
layers  of  sand  and  gravel,  and  clay  overlaid  with  mud.  After 
dredging  the  sites  of  the  piers  to  a  depth  of  30  feet  at  the 
sides  and  15  feet  along  the  centre  line  it  was  found  that 
very  much  longer  piles  were  required  than  were  shown  by 
the  preliminary  test  piles.  In  this  instance  the  penetration 
of  the  piles  varied  so  greatly  that  it  was  necessary  to  drive 
the  test  piles  50  feet  apart  each  way. 

DETAILS  OF  CONSTRUCTION 

The  durability  of  a  wooden  wharf  or  pier  depends  to  a 
very  great  extent  on  the  care  taken  in  the  details  of  the  de- 
sign to  prevent  as  far  as  possible  decay  caused  by  the  wetting 
of  the  timber  by  rain  water,  horses'  urine,  condensation,  etc. 
To  obtain  this  end,  all  places  where  water,  dust,  dirt,  and 
rubbish  can  collect  should  be  as  far  as  possible  eliminated. 
Pile  heads  where  they  project  beyond  the  sides  of  cap 
timbers  should  be  sloped  off;  all  rain  water  leaders  extend- 
ing down  through  the  deck  should  be  arranged  so  that  the 
discharge  will  not  fall  on  any  timber;  decks  should  be 
crowned  and  scupper  holes  provided  in  stringpieces  and  in 
the  deck,  wider  on  the  outside  than  on  the  inside  to  prevent 
clogging;  countersinks  for  bolt  heads  and  washers  in 
horizontal  surfaces  should  be  filled  with  pitch  and  all 
abutting  surfaces  should  be  drawn  tightly  together  with 
screw  bolts  in  order  to  reduce  as  much  as  possible  the 
penetration  of  moisture  between  the  adjacent  pieces. 
Places  on  top  of  timbers  on  which  dirt  sifting  through  the 
seams  in  the  deck  can  collect  should  be  filled  up  solid  with 
chocks  and  fillers.  Tenons,  mortises,  scarfs,  laps,  and  all 
other  surfaces  of  abutting  timber  should  be  brush-coated 
with  wood  preservatives,  and  pile  heads  should  be  liberally 
coated  with  asphaltic  cement  to  make  them  shed  water. 

As  it  is  impossible  to  protect  all  of  the  timber  from 
moisture,  it  is  important  to  make  it  possible  for  all  portions 
of  the  woodwork  to  dry  out  as  rapidly  as  possible  after 
becoming  wet  or  moist  by  providing  for  a  free  circulation 


34  WHARVES   AND   PIERS 

of  air.  The  result  of  preventing  such  drying  by  reducing 
the  circulation  of  air  has  been  described  in  Chapter  I. 

The  durability  of  a  wooden  wharf  or  pier  also  depends 
in  a  great  measure  on  its  stiffness  and  the  care  with  which 
the  details  are  designed  to  make  all  parts  of  the  structure 
act  as  a  unit  when  subjected  to  horizontal  forces  or  blows 
and  to  distribute  and  disperse  the  stresses  resulting  from 
such  forces  over  as  large  an  area  as  possible.  It  is  important 
to  oppose  all  stresses  with  wood  in  compression  as  far  as  it 
is  possible  to  do  so  and  not  to  depend  on  spikes  and  drift 
bolts.  The  number  of  joints  should  be  kept  as  low  as 
possible  by  using  the  longest  lengths  of  lumber  which  can 
be  obtained  at  reasonable  prices. 

The  rows  of  piles  should  be  cross-braced  as  far  down  as 
possible,  as  the  deflection  of  an  unbraced  pile  is  that  of  a 
cantilever  beam  and  varies  as  the  cube  of  its  unsupported 
length. 

The  following  description  of  wooden  piers  as  built  by 
the  Department  of  Docks  in  New  York  City  is  a  good 
example  of  those  in  which  the  above  principles  are  followed 
out  with  the  greatest  thoroughness.  (See  Fig.  1.) 

After  the  slips  alongside  the  pier  are  dredged  to  the 
required  depth  and  the  riprap  for  the  lateral  support  of 
the  piles  deposited  in  cases  where  it  is  required,  the  piles  are 
driven  with  floating  pile-drivers. 

The  outer  portion  of  these  piers  is  constructed  on  what 
is  known  as  the  double-pile  row  system  and  the  inner  por- 
tion on  the  single-pile  row  system.  In  the  single-row 
system  the  piles  are  spaced  about  6  feet  centre  to  centre 
in  each  transverse  row,  with  the  rows  10  feet  apart.  The 
outer  three  rows  of  piles  are  double  and  the  number  of 
the  piles  in  each  row  is. also  doubled,  making  the  spacing 
about  2  feet  6  inches.  The  double  rows  are  spaced  about 
23  feet  apart.  This  double-row  system  is  expensive,  as  it 
requires  extra  deep  longitudinal  " rangers"  or  stringers 
between  the  widely  spaced  pile-rows,  but  it  provides,  with 
the  planking  and  other  bracing  described  later,  an  enor- 


TIMBER   CONSTR  UCTION  35 

mously  strong  head  for  the  pier  where  the  greatest  horizontal 
stresses  occur,  together  with  wide  spaces  for  the  passage  of 
ice,  which  at  times  is  very  troublesome  in  this  locality,  and 
for  sewage,  which  in  many  cases  is  discharged  from  sewers 
under  the  pier  at  a  point  near  the  outer  end.  The  added 
strength  is  important  in  view  of  the  strong  currents  which 
occur  in  the  portions  of  the  water  front  used  for  shipping. 

The  piers  are  designed  to  carry  500  pounds  live  load  with 
a  loading  on  each  pile  not  exceeding  12  to  15  tons. 

The  piles  of  single-row  system  are  braced  transversely 
with  horizontal  and  inclined  planks  bolted  to  the  piles,  the 
former  being  at  the  elevation  of  mean  low  water.  The 
piles  are  faced  off  and  notched  to  give  a  good  bearing  both 
vertically  and  horizontally  for  these  planks.  The  inner 
faces  of  each  row  of  piles  in  the  double  rows  are  faced  off 
and  six-inch  plank  fitted  between  them,  each  plank  being 
spiked  to  every  pile.  The  outer  face  of  the  outermost  row 
is  similarly  planked  and  is  protected  against  abrasion  and 
still  further  strengthened  by  vertical  oak  sheathing.  This 
planking  on  the  double  rows  practically  forms  great  vertical 
girders  10  feet  deep  rigidly  connecting  the  heads  of  the 
piles  and  greatly  increasing  their  stiffness.  In  the  piers 
for  the  largest  steamships  where  floating  fenders  are  used 
the  piles  along  the  sides  of  the  pier  are  strengthened  by 
extra  planking  similar  to  that  on  the  double  rows. 

Each  double  row  is  further  stiffened  with  two  inclined 
bracing  piles  at  each  end  of  the  row  and  the  single  rows 
have  one  bracing  pile  at  one  end  alternating  on  the  sides  of 
the  pier. 

Armature  plates  of  |-inch  steel  are  fitted  around  the  end 
piles  of  the  double  rows,  the  space  beyond  them  being 
completely  filled  with  timber  accurately  fitted  together. 

The  side  caps  are  placed  2  feet  7  inches  below  the  top  of 
the  deck  and  these  extend  to  about  5  feet  9  inches  above 
low  tide.  These  timbers  extend  from  end  to  end  of  the 
pier  and  are  placed  at  this  elevation  to  prevent  scows 
and  lighters  of  low  freeboard  from  getting  under  it.  In 


36  WHARVES  AND  PIERS 

structures  where  the  side  cap  has  been  omitted  or  placed 
at  the  level  of  the  rangers  or  stringers  damage  has  been 
caused  by  such  vessels  being  caught  under  the  deck  and 
ripping  it  up  as  the  tide  rose  and  by  striking  the  side  piles 
with  their  square  corners  when  entering  the  slips  and 
knocking  them  out.  The  side  caps  are  secured  to  the  tops 
of  the  piles  by  mortises  and  tenons  and  large  dock  spikes 
driven  at  an  angle. 

The  transverse  rows  of  piles  are  capped  with  12-inch  by 
12-inch  timbers  with  mortises  fitted  over  tenons  on  top  of 
the  piles  or  with  two  6-inch  by  12-inch  planks  notched  into 
the  heads  of  the  piles  and  fastened  with  screw  bolts.  The 
latter  are  more  economical  in  labor,  saving  the  expensive 
mortising  and  tenoning,  are  lighter  to  handle,  rot  less  quickly, 
and  are  easier  to  obtain  in  the  better  qualities  of  lumber. 

On  the  cross  caps  are  placed  the  rangers  or  stringers. 
The  shed  rangers  which  support  the  shed  posts  or  columns 
are  laid  close  to  the  side  rangers  and  break  joints  with 
them  and  are  fastened  to  them  with  screw  bolts.  Interior 
rangers  are  placed  over  each  longitudinal  row  of  piles. 
Alternate  rangers  extend  from  end  to  end  of  the  pier  and 
the  others  over  the  double-pile  row  only.  Over  the  double- 
pile  rows  the  interior  rangers  are  12  inches  wide  by  26  inches 
deep  formed  by  one  12  by  12  inch  and  one  12  by  14  inch 
stick  or  by  two  12  by  12  and  one  2  by  12  fastened  together 
with  screw  bolts  and  spikes  and  notched  down  over  the 
caps  2  inches  to  prevent  sliding.  The  rangers  over  the 
single-row  system  are  of  12-inch  by  12-inch  sticks  or  two 
6  by  12  planks  bolted  together  with  |-inch  washers  between 
them  to  allow  for  air  circulation.  When  made  of  12  by  12 
lumber  the  rangers  are  bolted  and  fish  plated  to  take  stresses 
in  compression.  The  joints  are  placed  between  pile  rows, 
as  it  is  difficult  to  find  room  for  a  good  arrangement  of 
fastenings  if  they  are  located  over  the  cross  caps.  Those 
made  of  two  pieces  simply  break  joints  over  the  caps.  All 
rangers  are  fastened  to  the  cross-caps  with  dock  spikes 
driven  at  an  angle.  Over  the  double  rows  of  piles,  chocks 


TIMBER  CONSTRUCTION  37 

or  fillers  are  carefully  fitted  between  the  rangers,  making 
a  solid  mass  of  wood  from  side  to  side  of  the  pier  over  each 
cross  cap. 

On  the  rangers  and  at  right  angles  to  them  is  laid  a  deck 
of  4-inch  plank,  and  on  this  a  sheathing  or  wearing  surface 
of  3-inch  plank.  The  deck  planks  are  spaced  2  inches 
apart  except  over  the  cross-caps  and  chocking  between  the 
rangers,  where,  in  order  to  prevent  dirt  which  sifts  through 
the  sheathing  from  lodging  on  the  timber,  holding  moisture 
and  inducing  rot,  the  deck  planks  are  laid  close  together. 
Fillers  are  fitted  for  the  same  purpose  between  the  deck 
planks  where  they  cross  the  rangers.  The  sheathing 
plank  on  the  sides  of  the  pier  is  laid  at  right  angles  to  the 
deck  planks,  but  in  the  middle,  where  the  team  traffic  is 
heaviest,  it  is  laid  at  an  angle  of  45°  to  give  better  wear  and 
better  foothold  for  horses.  When  laid  at  an  angle  in  this 
manner  it  also  strengthens  the  deck,  making  it  act  as  a 
great  horizontal  girder.  Wire  spikes  are  used  for  fastening 
the  sheathing  on  account  of  their  cheapness  and  the  facility 
with  which  they  are  driven.  Bright  wire  nails  do  not  hold 
as  well  as  cut  nails  for  this  purpose,  but. this  objection  is 
overcome  if  those  coated  with  varnish  or  cement  are  used, 
or  if  they  are  rusted  by  immersion  in  salt  water  before 
driving.  As  the  sheathing  wears  out  and  has  to  be  renewed 
it  is  not  continued  under  the  backing  log  or  shed  sills,  long 
lengths  of  3-inch  by  12-inch  plank  being  laid  under  these 
timbers  to  bring  them  up  to  the  height  of  the  sheathing. 

" Backing  logs"  of  12-inch  by  12-inch  timber  are  placed 
on  the  edges  of  the  pier.  These  were  formerly  required 
by  law  on  all  wharves  in  New  York  City  to  prevent  carts 
and  trucks  from  backing  overboard,  and  the  custom  has 
prevailed  until  recently.  Such  a  timber  interferes  seriously 
with  handling  freight  by  means  of  the  longshoreman's  hand 
truck  between  the  wharf  and  vessels  which  have  their  decks 
lower  than  that  of  the  wharf.  A  timber  of  this  height  is 
unnecessary  on  the  parts  of  piers  which  are  covered  by 
sheds  and  may  be  replaced  with  one  six  inches  high  which  is 


38  WHARVES  AND  PIERS 

sufficient  to  prevent  men  slipping  overboard  when  handling 
mooring  lines. 

The  fender  system  consists  of  white  oak  piles  which 
resist  abrasion  better  than  pine,  driven  at  each  end  of  the 
cross  rows  of  piles  and  at  the  outer  corner.  The  piles  are 
faced  off  to  give  a  good  hearing  against  the  adjacent  timber 
and  the  tops  are  sloped  off  to  allow  the  water  to  run  off  and 
are  painted  to  prevent  rot  which  starts  at  the  top.  Covering 
the  tops  of  the  piles  with  zinc  or  copper  for  this  purpose 
is  effective  where  they  can  be  protected  from  the  depre- 
dations of  thieves.  In  some  places,  where  the  nature  of  the 
shipping  requires,  the  fender  piles  extend  4  or  5  feet  above 
the  deck.  Between  the  fender  piles  are  fitted  horizontal 
chocks,  and  in  the  23-foot  bays  vertical  chocks  are  fitted 
between  the  latter.  The  object  of  these  is  to  prevent  the 
guard  wales  of  tugs  and  similar  vessels  having  considerable 
sheer  from  catching  under  the  horizontal  chocks.  Where 
it  is  practicable  the  upper  horizontal  chock  is  replaced  with 
a  fender  pile  cap,  which  holds  the  piles  against  displacement 
and  covers  the  tops  and  keeps  them  dry. 

The  corner  fender  for  light  piers  shown  in  Fig.  2  has,  to 
a  large  extent,  been  abandoned.  The  heavier  design  shown 
is  now  standard  and  a  still  heavier  construction  is  used  on 
piers  for  very  large  steamships.  The  rounded  corner  facili- 
tates the  docking  of  long  vessels,  but  the  additional  piles 
obstruct  the  free  passage  of  ice  in  the  outer  bays.  As  cor- 
ner fenders  are  often  subject  to  heavy  wear  the  piles  are 
held  in  place  by  chains,  rather  than  by  bolts,  to  facilitate 
replacement. 

Foundations  for  shed  posts  for  single-story  sheds  are 
provided  by  extra  piles  either  in  the  pile  rows  or  just  out- 
side of  them.  Foundations  for  two-story  sheds  require  a 
cluster  of  piles.  They  are  cut  off  at  2  feet  above  mean  low 
water  and  are  capped  with  timber  to  support  a  concrete 
pedestal. 

The  types  of  mooring  posts  and  bitts  or  bollards  are 
shown  in  Figs.  124  and  125.  They  are  fastened  down  with 


TIMBER    CONSTRUCTION 


39 


Elevation    . 


Rounded  Corner  for  Large  Steamship  Piers 


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Zinc  Caps 
Standard    Corner 


Corner  for  Lighf  Piers 

Fig.  2.     Corners  for  Wooden  Piers,  Dept.  of  Docks, 
New  York,  N.  Y. 


40  WHARVES  AND  PIERS 

long  l|-inch  screw  bolts  extending  through  as  many  thick- 
nesses of  timber  as  possible,  the  spaces  between  the  timber 
being  carefully  chocked.  Special  foundation  timbers  are 
provided  for  the  large  mooring  posts  at  the  end  of  the 
pier,  and  the  rangers  over  them  are  held  down  by  strap 
bolts. 

Heavy  iron  straps  are  fitted  around  the  backing  log  at 
the  outer  corners  of  the  pier. 

In  many  piers  on  the  Pacific  coast  4-inch  by  14-inch  joists 
have  been  used  in  the  place  of  the  rangers  described  above. 
Such  joists  have  not  as  much  strength  considered  as  columns 
as  the  12-inch  by  12-inch  rangers  unless  their  lower  edges 
are  braced  against  buckling  by  means  of  what  is  known 
among  house  builders  as  "  bridging."  They  require  more 
spikes  for  fastening  to  the  caps  and  more  nails  in  the  deck 
planks  and  consequently  a  considerable  increase  in  labor, 
but  they  permit  of  the  use  of  lighter  deck  plank.  They 
have  a  distinct  advantage,  however,  when  required  to  be 
creosoted,  as  they  can  be  completely  impregnated  much 
more  cheaply  than  the  heavier  timbers,  but  on  account  of 
their  large  surface  area  and  small  cross-section  they  are 
much  more  easily  destroyed  by  fire. 

IRON  AND  WOOD  FASTENINGS 

Iron  and  wood  fastenings  for  lumber  in  wharves  consist 
of  drift  bolts,  screw  bolts,  dock  spikes,  nails  and  treenails. 
Iron  and  steel  spikes  and  bolts  last  a  long  time  submerged 
in  salt  water  when  protected  by  wood,  provided  they  are 
of  ample  cross-section,  but  rust  rapidly  where  exposed  to 
waves  and  currents.  It  is  the  practice  of  the  Bureau  of 
Yards  and  Docks  of  the  U.  S.  Navy  to  use  galvanized  bolts 
in  all  salt-water  wharves,  but  this  practice  is  uncommon  in 
other  work. 

Wooden  treenails  of  oak  or  locust  last  indefinitely  when 
kept  submerged  in  water  and  are  useful  for  fastenings 
which  cannot  be  easily  renewed.  The  timber  portion  of 
the  New  York  bulkhead  wall  contains  no  iron  whatever, 


TIMBER   CONSTRUCTION 


41 


all  parts  being  fastened  with  treenails,  some  of  which  are 
3  inches,  in  diameter  and  4  feet  long. 

Square  dock  spikes  such  as  are  shown  in  Fig.  3  require 


Shouldering  of  s;       .     R...  ^ ' iflr^W 

Brace  Pile  Head  Fastening  of  Corner  Mooring  Post 

£V 


Dock    Spike 


Fig.  3.     Details  of  Wooden  Piers,  Dept.  of  Docks, 
New  York,  N.  Y. 

less  boring  than  drift  bolts,  hold  better,  and  do  not  add 
much  to  the  cost  of  a  structure. 

Various  devices  for  fastening  fenders  and  similar  timber 
to  concrete  are  used.  A  sleeve  nut  such  as  is  commonly 
used  in  bridge  building  is  inexpensive  and  when  arranged  as 
shown  in  Fig.  4  allows  of  a  deep  and  positive  anchorage 


Standard  S/eeve  Nuf 
with  fyvo right  handed tftree> 


required 
Face  of  Concrete 


S fee/ Washer 


Fig.  4.     Bolt  for  Fastening  Fenders  to  Concrete  Walls. 

in  the  concrete  and  permits  the  easy  removal  of  the  bolt, 
Expansion  bolts  have  the  advantage  of  not.  having  to  be 
held  in  place  in  the  forms,  and  as  the  holes  for  them  need 
not  be  drilled  till  after  the  wood  is  bored  there  is  little  time 


42  WHARVES  AND  PIERS 

lost  in  locating  the  holes.  They  are  better  for  stone  masonry, 
however,  than  for  concrete,  as  the  holes  need  not  be  as  deep. 
For  concrete  the  shank  of  the  bolt  must  be  fitted  with 
sleeves.  Expansion  bolts  when  properly  put  in  place  will 
hold  in  tension  up  to  the  full  strength  of  the  bolt  at  the 
base  of  thread,  but  it  is  somewhat  difficult  in  ordinary  work 
to  obtain  such  results. 

SEWERS  IN  PIERS 

As  it  is  undesirable  to  have  sewers  empty  into  the  slips 
between  piers  it  is  necessary  to  support  them  in  the  sub- 
structures, as  shown  in  Fig.  70.  Sewer  boxes  of  circular  form 
for  pile  piers  are  made  of  creosoted  wood-stave  pipe  with  gal- 
vanized iron  bands.  Hatches  should  be  provided  at  proper 
intervals  to  permit  cleaning  and  inspection.  Reinforced 
concrete  pipe  also  affords  a  cheap  and  durable  material  for 
this  purpose  which  can  be  easily  and  cheaply  put  in  place. 


CHAPTER   IV 

RETAINING  WALLS   FOR  PIERS   AND   MARGINAL 

WHARVES 

FUNCTIONS  OF  WALLS 

FOR  solid-filled  piers  and  marginal  wharves  a  retaining 
structure  is  required  to  support  the  earth  or  filling  and 
must  afford,  either  in  itself  or  in  combination  with  a  plat- 
form of  some  kind,  a  vertical  face  of  sufficient  depth  to 
permit  vessels  to  lie  close  alongside.  Such  a  structure  must 
prevent  erosion  of  the  shore,  withstand  the  impact  of 
vessels,  currents  and  waves,  and  resist  overturning,  sliding, 
and  deformation  by  the  earth  or  other  filling  with  its  sur- 
charge of  merchandise. 

CALCULATION  OF  PRESSURES 

A  wharf  wall  presents  some  features  which  are  not  present 
in  ordinary  retaining  walls  on  land.  These  consist  in  the 
presence  of  water  on  both  sides  of  the  structure,  the  dimin- 
ished weight  of  the  wall  due  to  its  submergence  in  the 
water,  the  variety  of  materials  usually  found  in  the  filling, 
and  the  variation  in  the  weight  of  the  filling  due  to  the 
fact  that  part  of  it  is  submerged  and  part  not. 

The  calculation  of  the  pressures  on  such  walls  is  therefore 
complex  and  subject  to  many  more  uncertainties  than  that 
of  land  walls.  In  some  cases  it  is  impossible.  The  two 
methods  used  in  the  Department  of  Docks  in  New  York 
are  given  by  S.  W.  Hoag  in  the  Proceedings  of  the  Municipal 
Engineers  of  the  City  of  New  York,  1905,  as  follows: 

"The  conditions  given  are  approximate  cross-section  of 
submerged  or  of  non-submerged  wall,  submerged  sections 


44 


WHARVES  AND  PIERS 


and  non-submerged  sections  of  riprap  filling  and  of  earth 
filling,  and  a  surcharge  of  1000  pounds  per  square  foot 
(see  Fig.  5). 


Jjrx- 


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Fig.  5.     Method  of  Determining  Pressures  in  Sea  Walls,  Dept.  of 
Docks,  New  York,  N.  Y. 

"  Erecting  a  perpendicular  ad,  laying  off  the  prism  of 
maximum  thrust  of  riprap  by  the  plane  of  rupture  ae, 
prolonging  the  line  ae  to  n  and  the  corresponding  prism  for 
the  superimposed  submerged  earth  filling  by  the  plane  ek, 


RETAINING   V/ALLS  45 

which  we  shall  prolong  to  ra,  neglecting  the  change  in  plane 
of  rupture  for  non-submerged  earth  filling,  we  find  that  the 
limit  of  surcharge  to  be  considered  at  the  surface  grade  is 
contained  between  the  intercepts  d  and  m.  Considering 
now  everything  below  mean  high  water  as  submerged  and 
everything  above  mean  high  water  as  non-submerged,  let 
us  conduct  the  analysis  on  the  following  assumptions: 

"  Let  the  weight  of  riprap  in  air  be  assumed  at  107  Ib.  per 
cu.  ft. 

"  Let  the  weight  of  submerged  riprap  be  assumed  at  70  Ib. 
per  cu.  ft. 

"  Let  the  weight  of  earth  filling  in  air  be  assumed  at  110  Ib. 
per  cu.  ft. 

"  Let  the  weight  of  submerged  earth  filling  be  assumed  at 
66  Ib.  per  cu.  ft. 

"  Let  the  surcharge  be  assumed  at  1000  Ib.  per  sq.  ft. 

"  First.  Determine  the  weight  of  the  submerged  earth 
filling  cek,  and  replace  it  with  a  corresponding  weight  of 
submerged  riprap.  The  top  surface  of  the  latter  will  then 
be  cf'k. 

'  "Second.  Determine  the  weight  of  the  non-submerged 
earth  filling  cdmk  and  replace  it  with  a  volume  of  submerged 
riprap  of  equal  weight,  and  allow  it  to  take  its  position 
upon  the  first  reduced  volume  of  submerged  riprap.  The 
upper  surface  of  this  second  volume  will  then  be  cd'hTmkf. 

"  Third.  Take  the  surcharge  of  1000  Ib.  per  sq.  ft.  and 
erect  upon  the  top  surface  d'h'l'm  of  this  imaginary  bank 
of  submerged  riprap  a  prism  of  submerged  riprap  of  such 
a  volume  as  shall  equal  in  weight  the  surcharge;  the  upper 
surface  of  this  third  reduced  volume  will  then  be  d"ti'l"mf. 
We  now  have  the  area  a  d"h"l"mrnea  representing  in  volume 
all  of  the  back  filling  used  in  exerting  pressure  against  the 
wall  reduced  to  one  homogeneous  material,  namely,  sub- 
merged riprap  weighing  70  Ib.  per  cu.  ft.  But  in  order  to 
avoid  the  complication  arising  from  a  consideration  of  the 
two  planes  of  rupture  ae  and  em,  and  as  we  have  already 
reduced  the  back  filling  riprap,  let  us  adhere  to  the  plane 


46  WHARVES  AND  PIERS 

of  rupture  for  riprap,  namely,  an,  and  shift  the  material 
represented  by  the  area  enm  to  a  new  position  to  form 
part  of  the  prism  limited  by  the  plane  cm;  we  have,  making 
h"  the  new  position  for  d"V"  the  new  position  for  kl' ',  and 
m'm"  the  new  position  for  mn,  as  the  volume  to  be  con- 
sidered, the  weight  of  submerged  riprap  represented  by 
the  area  a  d"h"l'"m"na. 

"  The  centre  of  gravity  of  this  area  is  found  to  be  at  g' ',  and 
combining  the  weight  of  the  mass  through  g'  with  its  hori- 
zontal component,  we  find  the  horizontal  thrust  on  the 
back  of  the  wall  to  be  27,000  Ib.  applied  at  the  point  p. 
Combining  this  thrust  with  the  weight  of  the  wall  repre- 
sented by  the  vertical  line  65,300  Ib.  through  its  centre  of 
gravity,  we  obtain  the  resultant,  71,000  Ib.,  which  passes 
through  the  base  at  the  point  r. 

"In  determining  the  centre  of  gravity  of  the  wall  section 
it  is  of  course  necessary  to  consider  the  reduction  in  weight 
due  to  displacement  below  mean  high  water  of  the  two 
materials,  concrete  and  granite,  which  enter  into  its  con- 
struction, the  weight  of  the  non-submerged  portion  above 
mean  high  water,  the  weight  of  the  submerged  riprap  on  the 
steps  in  the  rear  of  the  wall,  the  weight  of  the  superimposed 
volume  of  non-submerged  riprap  and  of  earth  filling." 

The  other  method,  which  may  be  simple  in  cases  where 
riprap  does  not  form  part  of  the  filling,  is  illustrated  in 
Fig.  6  and  the  description  is  as  follows:  "Applying  the 
analysis  to  the  same  section  of  wall,  and  laying  off  the 
planes  of  rupture  for  riprap  ae  and  for  submerged 
earth  em,  as  before,  let  us,  first,  consider  the  pressure  of 
the  volume  represented  by  the  area  enme  with  its  super- 
imposed surcharge.  Combining  the  centres  of  gravity  of 
the  three  different  densities  represented,  that  is,  the  sub- 
merged earth  filling  efk,  the  non-submerged  earth  filling 
fhmk,  and  the  surcharge  hm,  13,600  Ib.,  we  obtain  the  re- 
sultant weight,  23,800  Ib.,  through  the  resultant  centre  of 
gravity  g'" .  Combining  this  weight  as  a  vertical  force 
through  g'"  with  its  horizontal  component,  we  get  the 


RETAINING   WALLS 


47 


resultant  thrust  on  eh,  from  which  we  obtain  the  hori- 
zontal thrust,  18,000  lb.,  against  the  vertical  plane  eh  at 
the  point  p. 

"  Again,  in  the  area  bdhe  combining  the  weights  and  centres 
of  gravity  of  the  different  materials,  namely,  submerged 
riprap  bee,  submerged  earth  filling  cfe,  non-submerged 
earth  filling  cdhf,  and  superimposed  surcharge  dh  equal  to 
12,000  lb.,  we  obtain 
the  resultant  weight 
28,600  lb.  through 
the  resultant  centre 
of  gravity  g" .  Com- 
bining this  force 
with  the  horizontal 
thrust  18,000  lb.,  we 
obtain  the  direction 
of  the  resultant 
which  strikes  the 
line  ad  at  the  point 
p"  with  a  horizontal 
thrust  of  18,000  lb. 

"Finally,  deter- 
mining the  weight 
and  centre  of  gravity  of  the  submerged  volume  of  riprap 
represented  by  the  area  abe  and  decomposing  the  resultant 
thrust  with  this  weight  12,430  lb.  as  the  vertical  compo- 
nent through  the  centre  of  gravity  gf ',  we  obtain  the  hori- 
zontal thrust  5400  lb.  applied  at  the  point  p"r. 

"Now  combining  the  two  horizontal  thrusts  at  p"  and 
p"1 ',  determine  the  resultant  horizontal  thrust  23,400  lb.  ap- 
plied at  a  point  p"" ',  and  combining  the  resultant  horizontal 
thrust  with  the  weight  of  the  wall,  determined  as  before 
through  its  centre  of  gravity  g,  we  get  the  resultant  thrust 
on  the  base  of  the  wall  70,000  lb.  applied  at  the  point  r." 

A  comparison  of  the  two  methods  shows  a  very  close 
agreement  both  in  the  amount,  direction,  and  point  of 
application  r  of  the  resultant  thrust. 


Fig.  6. 


Earlier  Method  of  Determining  Pres- 
sures in  Sea  Walls. 


48  WHARVES  AND  PIERS 

Another  good  article  on  this  subject  may  be  found  in 
Merriman's  American  Civil  Engineer  Pocket  Book. 

The  horizontal  resistance  of  sheet  piling  in  earth  is  a 
subject  on  which  there  is  little  in  engineering  literature  in 
the  English  language,  but  the  matter  is  well  treated  in  an 
article  by  Professor  Wolmar  Fellenius  in  Engineering  Record 
of  Sept.  20,  1913.  This  article  also  treats  of  wharf  walls 
of  the  platform  type. 

Mud  Waves.  —  Wherever  there  is  mud  which  can  move 
as  a  fluid  behind  a  retaining  structure  the  filling  will  produce 
a  wave  or  elevation  of  the  surface  of  such  material.  Mud 
acts  like  any  other  fluid  against  a  retaining  structure  except 
that  it  exerts  a  pressure  greater  than  water.  It  has  no 
angle  of  repose  and  therefore  will  exert  a  much  greater 
pressure  than  earth  or  any  similar  non-fluid  filling.  If 
filling  is  deposited  on  mud  from  the  shore  outwards  toward 
a  retaining  wall  it  will  push  the  mud  wave  ahead  of  it  and 
increase  the  elevation  of  the  mud  pressing  against  the 
wall  and  may  thus  increase  the  pressure  so  much  above  that 
of  the  filling  for  which  the  wall  is  designed  as  to  destroy  the 
structure.  This  has  happened  in  practice  so  frequently  that 
the  matter  demands  the  greatest  emphasis.  The  remedy  is 
to  deposit  the  filling  from  the  wall  toward  the  shore.  In 
this  way  the  mud  is  driven  away  from  the  wall  and  the 
increasing  pressure  due  to  the  increasing  height  of  the  wave 
is  resisted  by  the  increasing  width  of  the  bank  of  filling. 

The  depositing  of  the  filling  in  this  manner  is  usually 
much  more  inconvenient  and  expensive  than  depositing  it 
from  the  shore  outward,  in  that  it  is  often  necessary  to 
construct  temporary  roadways  for  the  purpose  and  this 
may  be  one  of  the  reasons  why  this  most  necessary  pre- 
caution is  so  often  neglected. 

GRAVITY  WALLS 

Gravity  walls  may  be  of  riprap,  cribwork,  stone  masonry, 
concrete  blocks,  mass  concrete,  caissons  of  concrete,  steel, 
or  wood,  or  various  combinations  of  these  materials. 


RETAINING   WALLS  49 

Walls  which  depend  on  gravity  alone  for  their  stability 
are  generally  costly  as  compared  to  other  types,  especially 
where  they  have  to  be  constructed  in  the  water.  Tie-rods 
and  anchors  placed  in  the  rear  are  often  used  to  assist  in 
taking  up  the  thrust  of  the  filling  and  permit  the  reduction 
of  the  cross-sectional  area  of  the  wall.  Gravity  walls  are 
particularly  suited  to  rock  or  other  hard  bottoms  where 
piles  cannot  be  driven.  Where  the  bottom  has  not  sufficient 
bearing,  however,  and  piles  can  be  driven,  a  gravity  wall 
may  be  placed  on  piles  cut  off  at  the  proper  height.  When 
a  wall  of  stone  or  concrete  blocks  is  built  with  a  pile  foun- 
dation some  method  of  obtaining  a  uniform  bearing  on 
all  the  piles  such  as  is  described  on  pages  90  and  122 
should  be  used. 

The  outshore  face,  of  retaining  walls  should  be  sloped 
back  in  order  to  bring  the  centre  of  gravity  as  near  the 
heel  as  possible,  thus  increasing  the  resistance  to  over- 
turning and  decreasing  the  necessary  cross-section.  Sloping 
the  face,  however,  makes  it  impossible  for  vessels  to  lie 
with  their  upper  parts  close  against  the  top  of  the  wall. 
Where  piers  for  the  use  of  large  vessels  are  built  in  front  of 
the  wall  and  only  small  vessels  are  moored  parallel  to  it, 
this  does  not  make  much  difference.  For  example,  in 
New  York  City,  the  slips  are  narrow  and  scows  and  lighters 
with  shallow  draught  lie  at  the  wall,  the  large  steamships 
being  berthed  alongside  piers  with  their  bows  inshore. 
The  walls  are  therefore  designed  with  as  much  slope  as  is 
possible  with  the  bows  of  the  steamers  coming  close  up 
against  them.  Where  large  steamers  are  to  lie  alongside 
a  wall  a  nearly  vertical  face  is  required,  and  on  a  sloping 
shore  it  is  usually  cheaper  to  place  the  wall  at  the  rear  of 
a  marginal  platform,  as  by  such  an  arrangement  its  cross- 
section  may  be  greatly  reduced. 

Riprap.  —  A  bank  of  riprap  forms  a  simple  form  of  re- 
taining wall  which  cannot  be  overturned  and  strongly 
resists  movement  by  sliding.  It  is  often  very  much  cheaper 
than  a  gravity  wall  of  concrete  or  stone  masonry.  The 


50 


WHARVES  AND  PIERS 


sloping  sides  of  such  a  bank,  however,  do  not  permit  its 
use  as  a  wharf  unless  it  is  combined  with  some  form  of 
structure  which  has  a  vertical  face. 

Where  the  depth  of  water  is  greater  than  that  required 
for  wharfage  such  a  bank  of  riprap  may  be  employed  to 
take  the  greater  part  of  earth-thrust,  a  masonry  wall  being 


Fig.  7.     Riprap  Wall  with  Upper  Portion  of  Granite  Masonry, 
New  York,  N.  Y. 

placed  on  the  front  edge  to  provide  the  necessary  vertical 
face.  As  this  comparatively  expensive  facing  need  be 
only  deep  enough  to  serve  the  requirements  of  shipping, 
such  a  combination  results  in  a  large  saving  over  a  masonry 
wall  of  the  full  depth.  A  good  example  is  shown  in  Fig. 
7  built  in  New  York  near  the  Battery  about  fifty  years 
ago. 

When  used  under  a  pile  platform,  a  riprap  wall  reduces 


RETAINING   WALLS 


51 


the  required  width  of  the  platform,  takes  a  major  portion 
of  the  earth-thrust,  reduces  the  stresses  in  the  bracing 
piles  or  tie  rods,  and  gives  lateral  support  and  stiffness  to 
the  piles.  A  design  for  a  very  inexpensive  wall  of  this 
type  is  shown  in  Fig.  8. 

A  bank  of  riprap  has  a  safe  angle  of  repose,  when  sub- 
merged, of  1  on  1  or  1  on  1J,  and  as  this  is  much  steeper 


M.H.W. 


M.L.W. 


Fig.  8.     Design  for  a  Cheap  Riprap  Wall  with  Pile  Platform. 

than  the  angle  of  repose  of  submerged  earth,  it  exerts 
much  less  thrust  against  a  vertical  surface  than  other  forms 
of  filling.  When,  therefore,  it  is  placed  behind  a  masonry 
wall  or  a  line  of  sheet  piling,  it  reduces  the  required  section 
of  masonry  and  the  stresses  in  the  ties  or  bracing  piles  used 
to  support  sheet  piling.  In  front  of  a  retaining  structure 
it  serves  the  same  purpose,  though  not  so  efficiently. 

A  notable  modern  example  of  a  riprap  wall  is  that  recently 
built  in  San  Francisco  and  illustrated  in  Fig.  9.     In  this 


52 


WHARVES  AND  PIERS 


case  the  mud  was  dredged  to  about  36  feet  below  low 
water.  The  main  part  of  the  wall  is  composed  of  riprap, 
as  shown  in  the  drawing.  A  retaining  wall  of  mass  concrete 
13  feet  high,  supported  on  wooden  piles  60  feet  from  the 
face  of  the  wall,  extends  from  low  water  to  the  street  level 
and  forms  the  upper  part  of  the  retaining  structure,  making 
a  smooth  and  tight  coping  for  the  riprap.  A  platform  on 
concrete  piles  covers  the  outer  slope  of  the  riprap  and 
forms  the  wharf  at  which  vessels  are  moored.  In  order  to 
provide  an  elastic  deck  which  would  not  be  injured  by  the 
settlement  of  the  riprap  and  piles  in  the  mud  bottom,  the 

beams  of  the  platform 
are  of  steel  and  the 
joists  and  deck  plank 
of  wood.  The  wooden 
piles  are  protected  from 
the  marine  borers  by 
the  riprap. 

The  wall  built  in  New 

art*    ;i    !!«  ,7A   ;    ;  ...  .  York    in   Places   where 

the  mud  is  very  deep, 

Fig.  9      Riprap  Wall    with  Concrete   Pile    described    on    page     88 
Platform,  San  Francisco,  Cal.  „ 

is  another  example  of  a 
wall  in  which  riprap  plays  a  leading  part. 

Crib  work.  —  One  of  the  commonest  forms  of  retaining 
structure  is  that  of  a  stone-filled  timber  crib  work.  Crib- 
work  is  best  suited  for  rock  or  other  hard  bottom  where 
piles  cannot  be  driven,  but  has  been  used  on  the  Harlem 
River  in  New  York  City  even  in  deep  mud.  In  its  least 
expensive  form,  consisting  of  a  cellular  box  built  of  round 
logs  notched  together  with  the  axe  and  fastened  with 
spikes  or  drift  bolts,  it  is  in  many  localities  one  of  the 
cheapest  forms  of  retaining  structure.  In  New  York  it 
costs  about  8  cents  a  cubic  foot,  exclusive  of  dredging. 
One  of  its  advantages  is  that  it  may  be  built  entirely  with 
hand  tools  and  does  not  require  any  expensive  equipment. 
It  is,  however,  subject  to  decay  above  half  tide  on  the  sea 


RETAINING   WALLS 


53 


coast  and  above  low-water  level  in  non-tidal  haroors,  and 
every  twelve  or  fifteen  years  the  decayed  portion  must  be 
torn  down,  rebuilt,  and  refilled. 

A  cribwork  wall  of  round  logs,  as  built  by  the  New  York 
Dock  Department,  is  shown  in  Fig.  10.  The  structure 
is  built  floating  in  the  water,  usually  over  or  near  the  site 
where  it  is  to  be  located.  The  bottom,  if  of  rock,  is  cleared 


Fig.  10.     Crib  Wall  of  Round  Logs,  New  York,  N.  Y. 

of  all  overlying  mud  and  the  cross-section  carefully  de- 
termined. The  bottom  of  the  crib  is  then  laid  out  to  fit 
the  surface  of  the  rock.  If  the  bottom  is  of  earth  it  is 
dredged  as  smooth  as  possible,  dredges  of  the  ladder  type 
being  superior  for  this  purpose.  A  layer  of  gravel  or 
broken  stone  may  be  deposited  and  smoothed  off  with 
straight  edges  to  level  up  small  irregularities  in  the  bottom. 
On  sloping  rock,  sliding  may  be  prevented  by  heavy  iron 
dowels.  The  cribs  are  built  with  cells  8  feet  long  and  5 
feet  wide,  a  sufficient  number  of  them  being  floored  over. 


54  WHARVES  AND  PIERS 

As  the  structure  is  built  up,  the  floored  cells  are  filled  with 
stone  and  the  structure  sinks.  When  it  is  high  enough  to 
reach  above  low  water  it  is  carefully  adjusted  in  location 
and  the  sinking  of  the  structure  is  completed  and  all  the 
cells  filled.  As  soon  as  the  crib  settles  and  conforms  to 
the  bottom  the  portion  above  the  water  is  completed. 
The  face  is  built  of  sawed  lumber  above  low  tide  to  give  a 
smooth  surface  and  is  protected  by  half-round  oak  fenders. 
The  longitudinal  logs  should  be  not  less  than  6  inches  in 
diameter  at  the  point  and  not  less  than  50  feet  long.  They 
should  have  long  laps  where  they  are  spliced.  The  trans- 
verse logs  should  be  not  less  than  10  inches  in  diameter  at 
the  front  in  the  upper  portion  which  is  subject  to  decay 
and  8  inches  in  the  other  portion.  Dock  spikes  of  ample 
size  to  allow  for  rust  should  be  liberally  used  at  all  inter- 
sections. Such  cribs  usually  require  a  width  of  not  less 
than  16  feet  at  the  top  for  heights  up  to  20  feet  and  may  be 
from  18  to  25  feet  wide  for  greater  depths.  The  portion 
below  the  limit  of  decay  may  be  made  wider  than  that 
above,  the  part  which  has  to  be  renewed  being  thus  reduced 
to  a  minimum. 

Cribs  of  this  construction  have  been  used  for  retaining 
walls  for  solid-filled  piers  in  soft  mud  of  great  depth,  but 
usually  some  other  form  of  wall  will  be  found  cheaper  and 
more  suitable  for  such  locations. 

Where  appearances  are  important  such  structures,  if  of 
large  section,  are  usually  unsatisfactory.  From  their  very 
nature  they  are  mere  baskets,  more  or  less  loose  in  the 
joints,  and  they  are  liable  to  bulge  both  vertically  and 
horizontally,  to  tip  forward  or  backward,  to  shrink  verti- 
cally, and  unless  the  bottom  is  very  carefully  prepared 
they  will  sink  into  it  more  or  less. 

Fig.  11  shows  typical  sections  of  large,  round-log  cribs, 
as  built  by  the  C.  R.  R.  of  N.  J.  at  Communipaw,  Jersey 
City,  N.  J.  They  are  from  30  to  50  feet  deep  and  are 
founded  on  hardpan.  In  these  cribs  vertical  logs  were 
placed  in  the  corners  of  the  pockets  to  prevent  vertical 


RETAINING   WALLS 


55 


shrinkage  and  the  floored  pockets  are  continuous  from 
front  to  rear,  instead  of  alternating,  as  in  the  previous  ex- 
ample. Where  it  was  expected  that  mud  would  flow  into 
the  trench,  stone  filling  was  deposited  as  soon  as  the  dredg- 


*~- >K 

Cro  ss  -  Section  of  Crib 


Section  A-A        Section  B-B       Section  C'C      Section  D'D 

Fig.  11.     Crib  Wall  of  Round  Logs,  C.  R.  R.  of  N.  J., 
Jersey  City,  N.  J. 

ing  was  completed  and  the  crib  placed  on  this  layer  of 
stone. 

On  the  New  York  Barge  Canal  cribwork  wharves  were 
built  with  concrete  walls  on  the  outer  edge  from  the  water 
line  up,  as  shown  in  Fig.  12.  A  large  proportion  of  the 
total  weight  of  the  structures  was  in  these  concrete  walls 
and  some  of  those  on  ordinary  earth  bottom  tipped  forward 
as  soon  as  the  concrete  was  deposited  and  kept  tipping  as 


56 


WHARVES  AND  PIERS 


often  as  more  concrete  was  added.  Such  action  may  be 
partly  prevented  by  supporting  the  cribs  on  piles,  by 
making  the  lowest  tier  of  longitudinal  logs  continuous, 
thus  increasing  the  bearing  surface,  and  by  temporarily 
loading  the  crib  with  stone  or  earth  and  completing  the 
earth  filling  as  far  as  possible  before  building  the  concrete 
wall. 

The  lowest  tier  of  transverse  logs  in  these  cribs  was  laid 

close  together  and  the  speci- 
fications required  that  the 
courses  of  logs  should  lay 
up  not  less  than  10  inches 
centre  to  centre  and  that 
logs  at  joints  should  have 
two  parallel  faces  not  less 
than  6  inches  wide. 

More  stable  cribwork  can 
be  made,  but  with  consider- 
ably increased  expense,  by 
accurately  dressing  the 
joints,  and  still  better  results 
can  be  obtained  by  using 
Fig.  12.  Crib  Wall,  with  Upper  For-  sawed  timber  for  the  cross 

tion  of  Concrete,  New  York  State   tieg    Qr    for    both    crogs    tieg 

and    longitudinals    and    by 
bolting  vertical  timbers  in  the  corners  of  the  pockets. 

A  crib  wall  for  a  large  coal  pier  built  at  Duluth,  in  1909, 
is  shown  in  Fig.  13.  The  site  of  the  pier  was  a  sand  bank, 
with  its  top  6  to  8  feet  below  water  containing  layers  of 
clay.  The  bottom  was  dredged  to  a  depth  of  26  feet  for 
the  crib,  which  was  of  sawed  lumber  21  feet  wide  with  tight 
front  and  rear  walls  of  10-inch  by  12-inch  timbers  and  was 
divided  into  pockets  6  feet  square.  The  top  of  the  crib 
was  6  inches  below  mean  low-  water  level.  Piles  were 
driven  to  support  the  reinforced  concrete  wall  which  sur- 
mounted the  crib,  in  order  to  provide  against  settlement. 
The  wall  was  tied  to  piles  driven  in  the  filling  40  feet 


RETAINING   WALLS 


57 


from  the  rear  face  of  the  crib  by  1J  rods  spaced  24  feet 
apart.  This  pier  carried  a  heavy  surcharge  of  coal  piled  on 
its  surface. 

The  crib  wall  surrounding  an  ore-pier  shown  in  Fig.  14 
was  built  at  Two  Harbors,  Minn.,  at  about  the  same  date. 
The  two  rows  of  cribs 
were  surmounted  by 
heavy  concrete  footing 
walls  resting  on  piles 
driven  inside  the  cribs 
and  carrying  the  columns 
of  the  ore  bins.  This 
structure  is  notable  for 
the  fact  that  the  work, 
which  included  the  set- 
ting of  forms  and  de- 
positing concrete  under 
water,  was  done  in  the 
winter  time  in  a  very 
cold  climate  and  for  the 
driving  of  foundation 
piles  at  very  close  inter- 
vals in  a  rockfilled  crib. 
There  were  two  rows  of 
cribs  of  sawed  lumber  16 
feet  wide  placed  about 


Fig.  13.     Crib  Wall  of  Sawed  Lumber  with 
Upper  Portion  of  Concrete,  Duluth,  Minn. 


22  feet  apart.  The  cribs  were 
tied  together  with  timber  walls,  thus  making  a  narrow  pier 
about  55  feet  wide.  The  tops  of  the  cribs  were  placed  at 
4.5  feet  and  the  tops  of  the  piles  were  cut  off  at  3.5  feet 
below  low  water.  A  sheet  of  burlap  was  placed  on  the  top 
of  the  piles  to  prevent  the  cement  being  washed  out  of  the 
concrete.  Forms  were  set  on  the  cribs  enclosing  an  area  of 
about  18  feet  by  50  feet  and  the  water  inside  the  forms 
heated  to  45  degrees  Fahr.  by  means  of  steam  under  60 
pounds,  pressure  supplied  through  a  hose.  The  concrete, 
mixed  in  the  proportion  of  1 :  2 :  4,  was  deposited  by  bottom 
dump  buckets  to  a  height  of  6  inches  above  water.  The 


58 


WHARVES  AND  PIERS 


upper  portion  of  the  concrete  was  then  completed  with  a 
1 : 2f : 5  mixture.  A  layer  of  reinforcement  was  placed  under 
the  bottom  of  this  upper  course  of  concrete,  and  steel  dowels 
were  placed  in  the  lower  course  to  provide  a  secure  bond 
between  the  two.  The  maximum  load  on  the  piles  under 
the  footings  was  24  tons.  The  space  between  the  cribs 
was  filled  with  stone  to  give  additional  stability  and  rigidity 
for  the  structure,  which  had  to  withstand  severe  stresses 
from  the  impact  of  vessels  and  from  the  stopping  of  heavy 
ore  trains  on  the  superstructure.  In  this  type  of  pier  the 
function  of  the  cribwork  is  merely  to  retain  the  filling 


i^ig.  14.     Crib  Wall  of  Sawed  Lumber  with  Upper  Portion 
of  Concrete,  Two  Harbors,  Minn. 

which  affords  lateral  support  to  the  piles.  In  piers  of 
more  recent  date  described  further  on  sheet  piling  is  sub- 
stituted for  the  cribwork. 

Another  type  of  large,  sawed-lumber  crib  of  more  recent 
design,  shown  in  Fig.  15,  was  built  at  the  Barge  Canal 
Terminal  at  Buffalo.  Here  the  water  was  deep  and  the 
bottom  of  rock  or  hard  material.  Where  there  was  rock 
it  was  levelled  off  with  broken  stone.  The  cribs  extended 
to  22  feet  below  mean  low-water  level  and  on  them  was 
placed  a  layer  of  concrete  blocks  extending  one  foot  above 
the  water  and  on  these  was  built  a  mass-concrete  wall. 
Though  the  weight  of  this  wall  was  small  in  proportion  to 
the  total  weight  of  the  structure  the  specifications  required 
that  the  crib  should  be  allowed  ample  time  to  settle  and 
that  it  should  be  levelled  up  with  additional  timber  on  the 
top  if  necessary  before  the  concrete  blocks  were  placed, 


RETAINING   WALLS 


59 


but  did  not  require  that  any  filling  be  deposited  before 
building  the  wall.     No  tie  rods  were  used  in  this  structure. 

Similar    construction  was    employed  at    Oswego,   N.Y., 
in  which  type  additional  stiffness  was  supplied  by  vertical 

timbers  in  the  corners  r gw 

of  the  pockets.  The 
pockets  in  this  crib 
were  10  feet  by  7  feet 
6  inches  in  area  and 
the  rear  face  of  the 
crib  was  built  in  steps, 
as  shown  in  Fig.  16. 
There  were  350  feet 
more  lumber  per  linear 
foot  of  wall  in  this 
design  than  in  that  of 
Buffalo  and  153  pounds 
more  steel  fastenings, 
which  made  a  very 
considerable  difference 
in  the  cost. 

The  stiffness  and 

Stability     of     Cribwork   Fig.  15.     Crib  Wall,  of  Sawed  Lumber  with 
may  also  be  increased        Upper  Portion  of  Concrete,  Barge  Canal 

by  filling  some  or  all  rermina1'  Buffal°'  N'  Y" 
of  the  pockets  with  concrete,  as  in  the  wall  of  the  North 
German  Lloyd  Steamship  Co.,  at  their  pier  at  Hoboken, 
N.  J.,  shown  in  Fig.  17.  The  cribwork  was  founded  on 
piles  driven  through  mud  to  rock  and  cut  off  at  22  feet 
below  mean  low  water.  It  was  built  of  sawed  lumber 
with  pockets  10  feet  square  filled  with  1:  2:  5:  concrete 
deposited  under  water  by  means  of  a  bottom  opening 
bucket  and  was  surmounted  by  a  stone  masonry  wall 
with  mass  concrete  backing.  This  method  of  construction 
permitted  an  examination  of  the  concrete,  which  was 
found  to  be  sound  and  strong.  Riprap  was  used  in  front 
and  in  rear  of  the  cribwork  to  aid  in  resisting  the  thrust 


60 


WHARVES  AND  PIERS 


of  the  filling,  and  cobble  was  used  to  consolidate  the  mud 
and  to  give  lateral  support  to  the  piles.  Corner  and  di- 
agonal braces  were  used  in  the  pockets  to  prevent  distortion 
of  the  cribwork  while  it  was  being  filled. 


'f*26  Screw  Both 
countersunk  or>  face  ofCr/'b 


Fig.  16.     Crib  Wall  of  Sawed  Lumber  with  Upper  Portion  of  Concrete, 
Barge  Canal  Terminal,  Oswego,  N.  Y. 

At  Depot  Harbor,  Ont.,  the  upper  portion  of  a  timber 
crib  wall  which  had  decayed  was  replaced  in  1904  with  new 
cribwork  made  of  12-inch  square  reinforced  concrete  logs 
as  shown  in  Fig.  18.  Table  II  on  page  18  gives  a  ready 
means  of  estimating  the  relative  economy  of  this  method. 
The  lower  portion  was  built  of  round  timber  in  the  usual 
manner.  The  main  concrete  logs  were  20  feet  long  and 
had  2J-inch  holes  moulded  in  them  at  varying  distances 


RETAINING   WALLS 


61 


apart,  arranged  to  allow  dowels  or  bolts  passing  from  top 
to  bottom  of  the  face  of  the  concrete  crib  to  be  inserted 
after  the  holes  were  filled  with  grout.  In  the  rear  the 
cribwork  was  stepped  and  the  members  fastened  together 
with  screw  bolts.  The  cross  ties  were  dovetailed  into 
facing  pieces  and  short  pieces  inserted  to  fill  the  spaces 
between  their  ends  and  make  the  facing  solid.  Concrete 
mixed  in  the  proportion  of  1:  2:  3  was  used  with  1^-inch 


Floor  Line  Bulkhead  Shed. 

Concrete,  l:2-4.  Founds  t  ion  for  Cross-  Walls 

>         f>nd. 

,-^f^  ,  Portland  Concrete  1:2'-S 

•v,^>\  ffi^j  [  (Cornerfosise  *' 6' every  30' 


Cobble  Stones. 


30' 


Fig.   17.     Crib  Wall  with  Concrete  Filling,  North  German  Lloyd  Co., 

Hoboken,   N.  J. 

stone.  A  similar  construction  was  specified  for  a  2400- 
foot  break- water  at  Port  Colburne. 

Quarried  Stone  Walls.  —  In  some  places  where  quarried 
stone  is  cheap  and  the  bottom  hard  and  reliable  this  material 
may  be  used  economically.  It  requires,  however,  careful 
levelling  of  the  bottom  with  gravel  or  broken  stone,  expensive 
floating  derricks  of  large  capacity,  and  a  considerable  amount 
of  work  by  divers. 

A  good  example  of  a  quarried  stone  wall  built  in  Boston 
in  1910  is  shown  in  Fig.  19.  The  pier  which  this  wall 
surrounds  is  situated  near  large  granite  quarries  located 
on  the  shore  and  suitable  floating  derricks  were  available. 


62 


WHARVES  AND  PIERS 


The  fact  that  the  climate  in  Boston  is  severe  and  the  tidal 
range  is  unusually  large  and  that  there  had  been  many 
failures  of  concrete  between  high  and  low  water  may  have 
had  considerable  influence  in  the  choice  of  granite  instead 
of  concrete. 

Concrete    Block    Walls.  —  Where    concrete    blocks    are 
cheaper  than  quarried  stone  they  may  be  used  in  a  similar 


%-4 


e 


r— rt 


~$  -Stf" 


fed 


Part-        Elevation. 

Fig.  18.     Crib  Wall  of  Reinforced  Concrete,  Depot  Harbor,  Ont. 

manner,  as  shown  in  Fig.  20.  The  large  concrete  blocks 
in  this  wall  are  of  70  tons,  weight.  The  portion  above  low- 
water  level  was  made  of  granite  with  concrete  backing,  as 
concrete  was  not  considered  sufficiently  durable  for  a  work 
of  such  a  monumental  character.  Riprap  was  placed  behind 
the  wall  to  reduce  the  thrust  of  the  filling  and  the  rock 
bottom  was  levelled  off  with  concrete  in  bags  placed  by 
divers,  with  a  top  coat  of  gravel  concrete  worked  smooth 
by  means  of  heavy  straight  edges.  The  water  at  some 
places  where  this  wall  was  built  is  36  feet  deep  at  mean 
low  tide. 


RETAINING  WALLS 


63 


A  wall  of  blocks  on  piles  is  shown  in  Fig.  21.  This 
type  of  wall  is  used  in  New  York,  where  the  piles  can  reach 
rock  and  where  the  bottom  is  sufficiently  firm  to  prevent 
any  horizontal  movement  of  the  piles.  The  bottom  is 
dredged  to  a  depth  of  20  feet  and  the  piles  cut  off  at  15 
feet.  Any  soft  material  is  pumped  or  washed  out  and  the 
space  between  them  filled  with  cobble  to  the  top  of  the 
piles.  A  concrete  mattress  as  described  on  page  90  is 
placed  on  the  heads  of  the  piles  just  before  the  base  blocks 


M.L.W. 


f  Ov- ••-•*•'.'•: vv;  Y>. 
T,'.N  .'..•    ^"^A-^- •••:-  •?'•"•  :./v 


Fig.   19.     Granite  Masonry  Wall,  Commonwealth  Pier  No.  6, 
Boston,   Mass. 

are  set.  Riprap  is  placed  behind  the  wall  to  diminish  the 
earth-thrust  and  in  front  of  it  to  aid  in  resisting  the  hori- 
zontal pressure. 

A  very  heavy  wall  of  hollow  concrete  blocks  filled  with 
concrete  and  stone  is  now  under  construction  at  Halifax, 
N.  S.  This  wall  forms  the  retaining  structure  for  a  mar- 
ginal landing  wharf  for  the  largest  ocean  steamships,  also 
for  a  solid-filled  pier,  aggregating  some  6500  feet  in  length. 
It  is  planned  to  build,  eventually,  five  more  piers  of  similar 
construction.  The  depth  of  water  at  the  face  of  the  wall, 
as  designed,  varies  from  45  feet  at  low  tide  for  the  major 


64 


WHARVES  AND  PIERS 


portion  to  30  feet  for  a  small  part  where  the  rock  excavation 
for  greater  depths  would  be  excessive. 

Among  the  conditions  under  which  this  wall  is  being 
built  are  the  presence  of  rock  over  the  entire  site  at  depths 


Fig.  20.    Concrete  Block  Wall  on  Rock,  West  52nd  St.,  New  York,  N.  Y. 

of  from  15  to  over  60  feet,  a  location  exposed  to  heavy 
swells,  a  large  amount  of  waste  rock  and  earth  available 
for  filling,  and  the  impossibility  of  driving  piles  on  account 
of  the  rock  bottom.  Speed  and  the  carrying  on  of  the 
work  during  the  winter  were  among  the  requirements. 

Five  general  types  of  structure  were  considered  in  adopt- 
ing the  chosen  design:  (1)  concrete  block  walls  with  mass- 


RETAINING   WALLS 


65 


concrete  filling;  (2)  concrete  caissons,  with  concrete  bottoms, 
floated  into  place;  (3)  a  solid  block  wall;  (4)  a  concrete 
platform  on  concrete  columns;  (5)  a  wall  of  cellular  concrete 
blocks. 


Fig.  21.     Concrete  Block  Wall  on  Piles  East  102nd  St.,  New  York,  N.  Y. 

The  first  plan  involved  difficulties  in  preparing  the  bottom 
and  required  expensive  temporary  staging;  the  second 
required  expensive  plant  for  launching,  winter  work  would 
have  been  impossible,  and  it  would  have  been  difficult  to 
make  a  good  bond  between  the  caissons  and  the  bottom; 
the  third  plan  had  the  same  objections  as  to  the  bottom 
and  plant;  the  fourth  plan  involved  risk  of  injury  during 


66 


WHARVES  AND  PIERS 


construction  and  would  have  cost  about  as  much  as  the 
fifth,  which  was  cheaper  than  the  first  three. 


895hell3  af-22-0'-—  -    -*i< 3/-O-* 


to.'1.  ..'0 

s'.? 

a^S 

*\ 
\ 
\ 

. 

/] 

o   •  .•  a 

i 

V 

Section  C-C 


Details  of  Concrete  Block 


Plan 


Fig.  22.     Wall  of  Hollow  Concrete  Blocks,  Halifax,  N.  S. 

The  adopted  design  consists  of  stacks  of  cellular  concrete 
blocks,  31  feet  long,  22  feet  wide,  and  4  feet  high,  weighing 
about  60  tons,  reinforced  against  handling  stresses  and 


RETAINING   WALLS  67 

those  existing  when  the  filling  is  completed.  These  blocks 
are  placed  on  the  prepared  foundation  by  a  very  large 
locomotive  crane  operating  on  tracks  placed  on  the  stacks 
of  blocks  already  in  place.  They  are  kept  in  vertical 
alignment  by  reinforced  concrete  guides  placed  in  triangular 
grooves  formed  in  the  sides  of  the  blocks. 

After  a  stack  of  blocks  is  in  place  all  the  pockets  in  the 
lower  layer  are  filled  with  concrete  and  those  in  the  second 
layer  are  filled  half  full.  Circular  holes  extending  through 
all  the  blocks  of  a  tier  are  then  filled  with  grout,  thus  filling 
and  bonding  the  horizontal  joints  between  the  blocks. 
Old  rails  are  placed  in  some  of  the  grout  holes  to  strengthen 
the  bond  between  the  layers  of  blocks.  The  front  row  and 
the  middle  transverse  rows  of  pockets  in  each  block  are 
also  filled  to  the  top  with  concrete,  making  a  solid  concrete 
buttress  in  each  tier.  The  other  pockets  are  filled  with 
rock  and  sand. 

The  two  upper  layers  of  blocks  were  made  narrower  than 
those  below  and  a  mass-concrete  wall  was  carried  up  behind 
a  granite  facing  from  low  water  to  the  grade  of  the  filling. 
Granite  was  used,  as  previous  efforts  to  obtain  concrete 
proof  against  destruction  by  frost  and  sea  water  between 
high  and  low  tide  in  the  extreme  climate  of  this  locality 
had  been  unsuccessful. 

A  bank  of  riprap  was  placed  in  the  rear  of  the  wall  to 
reduce  the  pressure  of  the  filling. 

The  bottom  is  prepared  in  several  ways,  according  to  the 
height  of  the  rock.  Where  the  latter  is  above  elevation 
45  feet  below  low  water,  the  rock  is  blasted  off  and  concrete 
pedestals  laid  under  the  corners  of  the  blocks  by  means  of 
a  large  diving  bell  which  permits  accurate  work  and  thorough 
inspection.  Where  the  rock  lies  far  below  the  45-foot  depth 
a  rubble  mound  is  placed  and  allowed  to  settle  for  a  year 
before  the  concrete  pedestals  are  laid  on  it,  as  described 
above.  Where  the  rock  is  only  a  few  feet  below  the 
bottom  of  the  blocks  a  mass  concrete  foundation  is  laid 
under  water  in  a  steel-sheet  pile  cofferdam.  Under  these 


68 


WHARVES  AND  PIERS  . 


conditions   the   pedestals   are   also   laid   and   levelled   off 
under  water. 


Design  B  -Reinforced  -Concrete  Caisson 
Floored  toPosifion 


Design  A 

Concrete  Blockwork  with 
Mass  Concrete  Heart 


Design  C -Solid  Block  Wall 


Section  of  Columns 


Design  D  -  Reinforced-Concrete  Deck 
on  Cylinders 

Fig.  23.    Rejected  Designs  for  Wharf  Wall,  Halifax,  N.  S. 

The  advantages  of  the  chosen  design  are  that  it  permits 
the  moulding  of  the  blocks  in  the  air,  the  rejection  of  all 
imperfect  concrete,  rapid  construction,  requires  compara- 
tively small  plant,  no  temporary  staging,  and  permits  the 
depositing  of  concrete  under  water  in  a  permanent  form 


RETAINING   WALLS  69 

under  the  best  conditions  for  such  work.  The  concrete  in 
the  lower  pockets  makes  a  strong,  uniform  bearing  for  the 
wall  on  the  foundation  and  gives  a  strong  bond  between 
the  two.  The  stacks  of  blocks  not  being  connected,  any 
vertical  settlement  which  may  take  place  during  construc- 
tion as  well  as  expansion  and  contraction  both  vertically 
and  horizontally  is  free  to  take  place. 

A  considerable  portion  of  the  wall  has  been  completed 
and  the  methods  described  are  reported  to  give  most  satis- 
factory results  in  rapidity  of  construction  and  accuracy  of 
alignment  and  levelling  of  the  stacks  of  blocks. 

Mass-concrete  Walls.  —  Walls  of  mass  concrete  may  be 
built  in  cofferdams  where  located  in  the  water,  and,  in  places 
where  the  slips  or  basins  are  to  be  excavated  in  the  land 
and  the  water  can  be  excluded,  they  may  be  built  in  sheeted 
excavations.  Such  walls  may  also  be  built  in  submerged 
forms,  the  concrete  being  deposited  in  the  water  by  means 
of  a  tremie.  The  latter  method  has  had  many  failures 
caused  by  the  washing  out  of  the  cement  from  the  concrete, 
and  those  that  have  been  successful,  for  the  portion  under 
water,  have  in  numerous  cases  not  resisted  the  action  of 
frost  between  high  and  low  tide. 

A  wall  of  this  type  constructed  in  a  cofferdam  is  shown 
in  Fig.  24.  The  depth  of  water  was  25  feet  at  mean  low 
tide.  The  cofferdam  was  somewhat  difficult  to  maintain 
and  the  difference  in  cost  between  that  and  the  block  walls 
was  so  small  that  the  block  type  was  built  in  subsequent 
sections  under  similar  conditions. 

The  New  York  State  Barge  Canal  affords  many  examples 
of  mass-concrete  walls  built  in  the  dry  or  in  cofferdams. 
Fig.  25  shows  the  general  form  adopted  for  retaining  walls 
for  the  canal  banks,  where  no  provision  is  made  for  sur- 
charge of  cargo. 

A  wall  44  feet  in  height  and  2005  feet  long  was  built  of 
mass  concrete  in  a  sheeted  and  braced  trench  at  Oak- 
land, California,  as  illustrated  in  Fig.  26.  The  facing  is  of 
richer  concrete  than  the  main  portion  of  the  wall  in  order 


70 


WHARVES  AND  PIERS 


to  make  this  portion  more  impervious  and  so  more  resistant 
to  the  action  of  sea  water.  The  fender  piles  are  stepped  in 
sockets  cast  in  the  lower  portion  of  the  wall  and  fastened 
by  bolts  extending  through  the  wall  in  a  2-inch  pipe  in  order 


Fig.  24.     Mass  Concrete  Wall,  East  116th  St.,  New  York,  N.  Y. 

to  facilitate  renewal.  The  earth  inside  the  trench  was 
removed  by  the  hydraulic  method,  water  being  pumped 
from  the  harbor  to  a  monitor,  the  earth,  as  it  was  loosened, 
sluiced  to  a  sump  and  pumped  out  to  the  deeper  portions 
of  the  harbor.  The  earth  outside  the  wall  was  dredged 
out  after  the  wall  was  completed. 


RETAINING   WALLS 


71 


A  good  example  of  mass-concrete  walls  supported  on  piles, 
29  feet  high  and  extending  17  feet  below  mean  low  water 


T 


Fig.  25.     Mass  Concrete  Walls,  New  York  State  Barge  Canal. 

with  a  platform  on  piles  as  shown  in  Fig.  27  was  recently 
constructed  in  San  Diego,  Cal.  The  bottom  was  excavated 
on  a  slope  under  the  platform  and  a  depth  of  20  feet 
obtained  at  the  face  of  the  wharf,  which  was  25  feet  wide. 
Riprap  was  used  to  prevent  erosion  ^  ^n^sedsurfa^ 

of  the  earth  slope  and  to  assist  some- 
what in  taking  the  thrust  of  the 
filling. 

Floating  Caissons.  -  -  Retaining 
walls  built  of  caissons  or  boxes  of 
wood,  steel,  or  reinforced  concrete, 
floated  into  place  and  then  filled 
with  various  materials,  have  been 
built  in  some  places. 

Two  such  walls  in  Denmark  have 
interesting  and  unique  features  which 
might  be  used  in  this  country.  One 
3300  feet  long  built  in  Copenhagen 
for  a  harbor  basin  is  shown  in  Fig. 
28.  There  are  twenty-two  reinforced  concrete  caissons 
made  of  a  1:  2:  3  mixture,  each  162  feet  long,  32  feet 
high,  and  16  feet  wide,  which  were  built  in  a  temporary 


5.    26.       Mass    Concrete 
Wall,  Oakland,  Cal. 


72 


WHARVES  AND  PIERS 


dry-dock  large  enough  to  contain  three  at  one  time.  The 
front  walls  are  10 J  inches  thick,  those  at  the  ends  of 
the  caissons  13|  inches  and  the  partitions  only  7|  inches. 
The  depth  of  water  at  the  front  of  the  wall  is  31  feet.  The 
most  interesting  feature  is  the  granite-faced  wall  extending 
from  just  above  the  water  level  to  the  top,  which  projects 
in  front  of  the  face  of  the  caissons  and  protects  them  from 
the  impact  of  vessels.  The  portion  of  the  wall  subject  to 
freezing  is  protected  by  a  thin  facing  of  granite.  In  a 
similar  wall  built  several  years  previously  at  Norre  Sundby 


<5'^V^  •  6'-6"^>-lo^6L 

^                    ff4-/,sf/^ 

\ 

r 

Concrete 
Wa/T^ 

: 

Drain 
Hole 
2'Dia> 

::; 

u; 

: 

Part  EleywHon  of  Bulkhead         j 


Fig.  27.     Mass  Concrete  Wall,  with  Concrete  Pile  Platform,  San  Diego,  Cal. 

in  water  24|  feet  deep  the  exterior  walls  were  notable  for 
their  extreme  thinness,  being  only  5.1  inches  thick  at  the 
bottom  and  3.5  inches  at  the  top.  The  caissons  in  this  case 
were  built  on  shore  and  launched  by  means  of  slipways. 
In  both  walls  the  caissons  were  filled  with  sand. 

Another  example  in  which  the  walls  are  much  thicker  is 
that  of  the  wharf  walls  of  the  new  Welland  Canal  shown 
in  Fig.  29.  The  caissons,  which  were  110  feet  long,  38 
feet  wide,  and  34  feet  high,  were  open  at  the  bottom  but 
were  fitted  with  temporary  wooden  bottoms  to  keep  them 
afloat  while  they  were  towed  to  the  site  and  sunk.  They 
were  built  in  floating  pontoons  which  were  arranged  so  that 
they  could  be  taken  apart  and  removed  as  soon  as  the 


RETAINING   WALLS 


73 


caissons  would  float.     As  the  stresses  in  the  walls  while 
afloat  were  much  greater  than  after  the  caissons  were  in 


B 


Z&± 


SECTION  CC 


^wr  T 
. 2JO* __>) 

SECTION  AA 


A 

SECTION  BB 


Fig.  28.     Wall  of  Concrete  Caissons,  Copenhagen,  Denmark. 

place  and  filled  with  stone,  the  pockets  were  braced  during 
transportation  with  timber,  which,  with  the  wooden  bottoms, 
was  removed  as  soon  as  the  caissons  were  in  place  and  used 
over  and  over.  The  caissons  rested  on  windrows  of  stone 


74 


WHARVES  AND  PIERS 


placed  on  the  dredged  bottom  under  the  longitudinal  walls, 
and,  after  the  temporary  wooden  bottom  and  bracing  were 
removed,  they  were  filled  with  dredged  material.  The 
outer  edge  of  the  row  of  caissons  was  surmounted  by  a 
mass-concrete  wall  built  after  settlement  ceased.  Fifty- 
three  such  cribs  were  built,  and  their  great  number  made 
rB 


•IIO'A'- 
Plan 


Interior  Wall- 


& 


HLp 


&& 


Section  A-A  Section  B'B  Secfion  Showing  Method  of  Racing  Earth  Fill 

Fig.  29.  Wall  of  Concrete  Caissons,  Welland  Canal,  Ont. 

this  form  of  construction  economical.  The  most  notable 
feature  of  this  wall  was  the  saving  in  concrete  due  to  the 
ingenious  and  novel  use  of  temporary  wooden  bottoms  and 
bracing  to  resist  the  stresses  while  the  caissons  were  being 
floated  into  position.  It  is  stated  that  certain  features  of 
this  design  have  been  patented. 

A  wall  at  Victoria,  B.  C.,  of  reinforced  concrete  caissons 
or  cribs,  as  they  are  locally  designated,  in  which  the  bottoms 
of  the  caissons  were  of  concrete  and  the  walls  sufficiently 


RETAINING   WALLS 


75 


strong  to  withstand  the  water  pressure  when  the  caissons 
were  afloat,  is  shown  in  Fig.  30.  In  this  case  the  cribs  were 
85  feet  long,  35  feet  wide,  and  39  feet  high  and  the  outer 
walls  were  20  inches  thick.  They  were  braced  with  two 
longitudinal  walls  and  with  transverse  walls  every  10  feet. 
Additional  deep  beams  between  the  transverse  walls  dis- 
tribute the  pressure  of  the  mass-concrete  wall,  12  feet  high 
and  16  feet  above  the  water,  which  is  built  on  top  of  the  caisr 

K         ..=....-., Q0>-0» ^ 


I 


Longitudinal  Section  of  Crib 


£1.  0.0 


Section  of  Pier 
Fig.  30.     Wall  of  Concrete  Caissons,  Victoria,  B.  C. 

sons.  The  cribs  drew  28  feet  of  water  when  launched. 
The  first  ones  were  built  in  a  floating  dry  dock,  which  was 
wrecked  by  premature  flooding,  and  the  later  ones  were 
constructed  on  a  marine  railway. 

These  cribs,  fifty-four  in  number,  were  used  for  enclosing 
solid-filled  piers  800  to  1000  feet  long  and  250  feet  wide  in 
water  having  a  maximum  depth  of  65  feet,  and  a  novel 
feature  in  their  construction  was  the  preparation  of  the 
stone  mound  foundation  on  which  the  caissons  rest.  Large 
stone  was  deposited  by  deck  scows,  which  slid  their  load 


76  WHARVES  AND  PIERS 

overboard  when  water  was  admitted  to  longitudinal  com- 
partments located  along  the  sides  of  the  hulls,  to  an  eleva- 
tion of  36  feet  below  the  water  surface.  Any  rock  projecting 
above  this  level  was  removed  with  a  clamshell  or  orange- 
peel  dredge  bucket.  The  mound  was  then  levelled  up  with 
gravel  to  elevation  -35  and  the  gravel  smoothed  off  by 
means  of  a  plough  suspended  from  a  pile  trestle  driven 
into  the  riprap.  The  plough  was  a  heavily  braced  timber 
structure,  weighted  with  stone  and  having  a  pointed  end 
shod  with  iron. 

It  was  hung  by  rods  from  beams  arranged  to  move 
along  the  top  of  the  trestle-work  and  when  adjusted  at  the 
proper  height  it  was  hauled  along  the  trestle,  ploughing 
off  any  gravel  above  the  required  elevation. 

A  comparison  of  the  two  foregoing  cases  is  interesting. 

Reinforced  concrete  caissons  for  a  breakwater  at  Algoma, 
Wis.,  24  feet  long,  15  feet  wide,  and  12  feet,  4  inches  high 
were  built  by  day  labor  for  $17.66  a  cubic  yard  for  the 
concrete.  The  wall  of  caissons  with  pile  foundation,  con- 
crete filling,  and  superstructure  cost  $75.67  per  linear  foot. 

RELIEVING  PLATFORM  WALLS 

Relieving  platform  walls  may  be  defined  as  those  in  which 
a  platform  on  piles,  in  combination  with  banks  of  riprap, 
masonry  walls,  or  lines  of  sheet  piling  forms  a  part  of  the 
structure  and  relieves  the  wall  itself  of  the  pressure  of  the 
live  load  and  of  any  filling  on  the  top  of  the  platform,  and 
of  a  part  of  the  horizontal  pressure  of  the  filling  beneath. 
The  platform  may  be  located  at  or  near  the  level  of  low  water 
or  may  form  the  deck  of  the  wharf. 

The  main  object  of  the  platform  in  retaining  structures 
is  to  diminish  the  cost  by  the  elimination  or  reduction  of 
the  thrust  which  is  the  necessary  accompaniment  of  any 
wall  which  has  a  vertical  facing  on  the  front  edge  for  the 
whole  depth  required  by  shipping.  This  object  is  attained 
in  two  ways:  first  by  building  the  platform  over  a  sloping 
bank,  either  natural  or  artificial,  having  its  face  at  a  safe 


RETAINING   WALLS  77 

angle  of  repose,  and  second,  by  placing  the  platform  behind 
a  wall  of  masonry  or  sheet  piling. 

If  the  first  method  is  used  the  platform  may  be  placed 
over  a  bank  of  riprap  which  retains  the  filling,  as  in  Fig. 
32  or,  if  the  wall  be  built  inside  the  natural  shore  line, 
it  may  be  placed  over  a  dredged  slope,  protected  against 
erosion  by  a  revetment  of  stone,  as  in  Fig.  37.  In  some 
cases  such  a  platform  has  been  built  over  an  existing  sloping 
shore  without  any  dredging  or  revetment.  A  low  wall  of 
masonry  or  sheet  piling  may  be  placed  at  the  rear  of  the 
platform  in  order  to  reduce  the  width  of  the  latter  and  to 
provide  a  tight  bulkhead  to  retain  the  filling  at  a  point 
where  the  riprap  is  thin. 

This  type  of  wall  is  particularly  suitable  for  tidal  waters 
where  the  range  of  tide  is  not  too  great,  but  platform  walls 
of  the  first  type  are  open  to  the  same  objections  that  apply 
to  any  wooden  structure  in  waters  where  marine  borers  are 
met  with. 

An  example  of  a  platform  wall  built  at  some  distance 
from  the  shore  is  that  built  at  Gowanus  Bay,  Brooklyn, 
N.  Y.,  and  shown  in  Fig.  31.  A  hard  sand,  clay,  and 
gravel  bottom  was  found  at  17  feet  below  low  water,  over- 
laid with  mud  12  or  15  feet  deep.  Marine  borers  were 
absent  and  there  was  no  objection  to  the  use  of  untreated 
piles  below  half  tide.  A  trench  was  excavated  to  a  depth 
of  17  feet,  for  a  distance  of  25  feet  in  rear  of  the  face  of 
the  wall,  with  a  natural  slope  on  the  inshore  side.  The 
slips  between  the  piers,  which  are  to  be  built  in  front  of  this 
wall,  were  dredged  to  35  feet  depth  and  a  berm  50  feet 
wide  at  the  bottom  was  left  in  front  of  the  wall  opposite 
the  slips.  The  piles  were  then  driven  and  capped  and 
the  riprap  deposited.  After  some  time  had  elapsed  to  allow 
for  settlement  the  riprap  was  brought  up  to  the  under  side 
of  the  platform,  the  deck  laid,  and  the  concrete  wall  built. 
The  area  back  of  the  wall  was  then  filled  with  selected  sand 
and  gravel  pumped  from  the  slips.  Some  difficulty  was 
caused  by  the  filling  washing  through  the  riprap  at  its 


78 


WHARVES  AND  PIERS 


junction  with  the  platform,  where  the  thickness  of  riprap, 
through  which  the  filling  passed,  was  a  minimum.  This 
could  have  been  prevented  by  careful  grading  of  the  riprap 
to  make  it  sufficiently  tight  to  hold  the  filling,  by  depositing 
a  bed  of  selected  dry  filling  over  the  riprap,  or  by  placing  a 
vertical  sheeting  at  the  rear  edge  of  the  platform. 

It  is  important  to  make  the  dredged  trench  of  sufficient 


//?<?  "Spikes, 


I 
I 
'-^6-a"- -.^ *4 

Fig.  31.     Platform  Wall,  Gowanus  Bay,  Brooklyn,  N.  Y. 

width,  in  the  rear  of  such  a  wall,  to  prevent  the  riprap  from 
sliding  and  pushing  the  piles  out  of  plumb.  Where  such 
a  wall  encloses  a  large  tidal  area  to  be  filled  by  pumping, 
special  attention  must  be  paid  to  the  management  of  the 
filling  and  to  the  openings  for  controlling  the  effluent  of 
the  pumps  and  the  flow  of  the  tide  through  the  wall,  in 
order  to  prevent  the  washing  of  the  dredged  material  through 
the  riprap. 

This  wall  was  designed  for  a  live  load  of  500  pounds  per 
square  foot  and  required  piles  to  be  placed  4  feet  longi- 


RETAINING  WALLS 


79 


tudinally  and  4  feet  transversely  on  the  average  to  give  a 
loading  not  exceeding  12  short  tons  on  the  piles. 

The  concrete  was  made  with  gravel  in  the  proportion  of 
1:  2J:  5  except  a  facing  of  1:  1J  mortar  6  inches  thick  ex- 
tending up  to  above  high  water.  It  is  expected  that  the 
dense,  rich  face  will  withstand  the  action  of  frost  in  the 


^•;^fc'?:--3W'';''vf:'v'-'-^'ij'A''  -^—^  •..'•  .:-.V.^-^4~.: 

.  :•  .;• 


Fig.  32.     Platform  Wall,  Hunts  Point,  New  York,  N.  Y. 

salt  water.     No  concrete  was  allowed  to  be  deposited  when 
water  was  in  the  forms. 

Another  example  is  that  of  a  very  long  wall  at  Hunts 
Point,  New  York,  illustrated  in  Fig.  32.  Here  the  de- 
sired depth  was  30  feet.  Sand  mixed  with  gravel,  or  rock, 
was  found  at  depths  varying  from  25  to  65  feet,  over- 
laid with  mud  extending  up  to  from  1  to  4  feet  below 
low  water.  A  trench  was  dredged  to  30  or  35  feet  below 
low  water  or  to  the  hard  bottom,  where  it  existed  at  lesser 
depths.  The  piles  were  then  driven  and  capped.  Railroad 
tracks  were  laid  on  a  temporary  trestle  placed  on  the  caps, 
and  stone  from  the  subway  excavation  then  in  progress 


80 


WHARVES  AND  PIERS 


near  by  was  brought  in  dump  cars  and  deposited  between 
the  piles.  The  greatest  care  was  taken  in  depositing  this 
stone  to  prevent  the  displacement  of  the  piles.  A  second 
deposit  of  stone  in  the  rear  of  the  piling  was  made  from 
scows,  and  the  final  deposit  was  then  sealed  with  ashes  and 
street  sweepings  and  the  area  behind  the  wall  filled  with 
mud  pumped  from  in  front.  The  necessity  for  removing 
the  mud  before  depositing  the  stone  was  shown  by  the 
fact  that  an  attempt  to  make  a  rock  fill  for  a  dike  on  the 


Fig.  33.     Details  of  Fig.  32. 

side  of  the  filled  area,  by  dumping  the  stone  from  a  trestle 
without  removing  the  mud,  resulted  in  the  pushing  out  of 
the  piles  and  the  destruction  of  the  trestle. 

The  tidal  area  enclosed  by  the  wall  and  banks  of  stone 
partially  sealed  with  fine  material  as  described  above  was 
so  large  that  the  size  of  flood  gates  to  be  of  any  use  would 
have  been  prohibitive  and  the  final  closing  of  the  retaining 
structures  was  accomplished  with  considerable  difficulty. 

A  feature  of  the  filling  was  its  solidification  by  mixing 
ashes  and  street  sweepings  with  the  soft  mud.  The  mud 
thus  consolidated  had  sufficient  bearing  power  to  support 
tracks  for  transporting  and  distributing  the  street  refuse. 

The  platform  is  notable  for  the  careful  design  of  the 


RETAINING   WALLS 


81 


connection  between  the  platform  and  the  bracing  piles, 
which  is  shown  in  the  illustration,  and  for  the  front  portion 
being  lower  than  that  in  the  rear  of  the  concrete  wall.  This 
was  for  the  sake  of  the  appearance  at  low  tide,  as  it  was 


Fig.  34.     Platform  Wall,  Wallabout  Basin,  Brooklyn,  N.  Y. 

considered  desirable  to  have  the  concrete  extend  down  to 
as  near  low  water  as  possible. 

Where  rock  was  found  at  such  depths  that  piles  could  not 
be  driven  in  the  natural  bottom,  the  mud  was  dredged,  a 
layer  of  stone  deposited,  and  the  piles  driven  through  the 
stone. 


82 


WHARVES  AND  PIERS 


Heavy  wooden  sheet  piling  supported  by  bracing  piles 
is  the  principal  feature  of  the  wall  at  Wallabout  Bay,  New 
York  City,  shown  in  Fig.  34.  This  wall  has  no  anchors 
or  tie  rods.  It  was  built  inside  the  shore  line,  and  the 
channel  outside  it  was  excavated  after  it  was  built. 

A  wall  at  Los  Angeles,  Cal.,  is  illustrated  in  Fig.  35.  In 
this  case  riprap  both  behind  and  in  front  of  a  line  of  sheet 


SurfofGrVL 


P/feAnchor 

and  Shed  Foundation 


One  double 
^Surface  n-Jnxk     jj.  ' '  "_EIJ4_ 


around  piles 
"anc/Japped 


Section 
A -A 


Fig.  35.     Reinforced  Concrete  Platform  Wall  with  Concrete  Sheet  Piles, 
Los  Angeles,  Cal. 

piling  takes  a  considerable  portion  of  the  earth  pressure. 
All  of  the  structure  except  the  anchor  piles  is  of  reinforced 
concrete  and  none  of  the  structure  is  destructible  by  fire, 
decay,  or  marine  borers  except  the  fendering.  The  fender 
piles  are  creosoted. 

A  design  for  a  wall  to  be  built  inside  the  existing  shore 
line  is  shown  in  Fig.  36,  In  this  case  the  width  of  the 
platform  was  decreased  to  a  minimum  by  using  riprap  to 
retain  the  filling,  and  the  amount  of  riprap  required  was 
comparatively  small,  as  it  was  possible  to  dredge  the  bank 


RETAINING   WALLS 


83 


on  a  slope.  Care  should  be  exercised  in  such  a  wall  to  pre- 
vent the  riprap  pushing  out  the  piles.  It  is  better  to 
deposit  some  or  all  of  the  riprap  before  driving  the  piles. 

A  wall  at  Providence,  R.  I.,  in  which  sheet  piling  retains 
the  filling  and  riprap  is  used  principally  to  prevent  erosion 


Z*22"Oock  Spike,  YJ/2  It/2  "Backing Log 
*li22"Bo/t.    ^ 


8  wil-h  Anchor. 
3  Facing -/:/£, 


?"Toe  Piece 
2  "Oak  Treenaf, 


Piles  Spaced  5'ctoC. 
Longitudinally 


Fig.  36.     Design  for  a  Platform  Wall  inside  the  Shore  Line. 

is  shown  in  Fig.  37.  This  wall  provided  30  feet  of  water 
at  low  tide  with  a  platform  30  feet  wide.  All  of  the  piles 
and  lumber  in  this  wall  were  creosoted  except  the  fender 
piles,  the  bearing  piles  having  16  pounds,  and  the  lumber 
14  pounds  of  oil  per  cubic  foot.  The  masonry  part  of  the 
wall  was  of  granite  ashlar  backed  with  concrete,  as  the 
climate  is  severe  on  concrete  exposed  to  freezing.  The 


84 


WHARVES  AND  PIERS 


caps  were  fastened  to  the  piles  by  wooden  dowels  or  tree- 
nails and  all  metal  fastenings  were  of  galvanized  refined 
iron. 

Bracing  piles  in  such  walls  are  not  absolutely  necessary, 
as  the  piles,  stiffened  and  supported  by  the  riprap,  may  be 
sufficient  to  take  the  thrust  of  the  portion  of  the  filling 
above  the  platform,  as  shown  in  Fig.  38  at  Whale  Creek, 


•j-; — j  JM Y| 


Fig.  37.     Platform  Wall,  Providence,  R.  I. 

New  York,  N.  Y.  This  wall  has  been  built  several  years 
and  shows  only  a  slight  bulging,  due  to  a  soft  spot  in  the 
bottom  which  was  not  dredged  out.  It  has  not,  however, 
been  subjected  to  any  very  heavy  live  load. 

Earth-filled  cribwork  walls  on  the  edge  of  the  platform 
were  formerly  used  instead  of  masonry.  In  some  cases  the 
cribwork  was  extended  back  of  the  platform  in  order  to  resist 
the  outward  thrust.  Such  construction  is  only  temporary 
and  failures  have  resulted  from  the  rotting  of  the  transverse 


RETAINING   WALLS 


85 


tie  logs.  The  decrease  in  the  cost  of  concrete  and  the 
increase  of  its  durability  in  sea  water,  due  to  better  mixing 
and  proportioning,  render  it  more  economical  than  cribwork 
for  this  purpose  under  ordinary  conditions. 

A  wall  for  12  feet  depth  of  water  for  a  Barge  Canal  Ter- 
minal at  Schenectady,  N.  Y.,  with  a  reinforced  concrete 
platform,  is  shown  in  Fig.  39.  It  was  built  in  a  dry  trench 
excavated  within  the  shore  line  of  the  Mohawk  River. 
Timber  piles  were  substituted  for  the  concrete  piles  shown 


-•  Granite  Block  Pavement 
|          £/.  +353 


Pile  Bents  Spaced 
5'-C.'toC. 


1 


Cross    Section 
Fig.  38.     Platform  Wall,  Whale  Creek,  Brooklyn,  N.  Y. 

in  the  illustration.  A  similar  wall,  with  a  wooden  plat- 
form, for  another  terminal  at  Whitehall,  N.  Y.,  is  shown 
in  Fig.  40.  These  designs  were  preferred  for  freight  wharves, 
on  account  of  their  cheapness,  to  the  standard  type  of 
gravity  concrete  retaining  walls  used  all  along  the  canal 
wherever  a  vertical  face  was  required. 

A  novel  type  of  platform  wall  over  a  sloping  bank  recently 
built  at  Savannah,  Ga.,  is  shown  in  Fig.  41.  The  main 
feature  of  this  design,  which  was  patented  by  William  M. 
Torrance,  is  the  sloping  platform  of  reinforced  concrete 
supported  on  piles.  The  dead  load  on  the  piles  is  less  than 


86 


WHARVES  AND  PIERS 


with  the  horizontal  platform  and  superior  economy  is 
claimed  for  this  type  over  that  shown  in  Fig.  36. 

A  similar  wall  in  which  concrete  piles  support  the  sloping 
platform  without  the  use  of  cross  walls  is  illustrated  in 
Fig.  42.  This  is  a  type  used  in  Rio  Janeiro. 

The  wall  of  the  Bush  Terminal  in  Brooklyn,  N.  Y.,  in 


Pool 


.  O.S6 ° "Bars, 22  tg.  12 c. to. b. 
\0.66°"» 


Fig.  39.     Wall  with  Wooden  Piles  and  Reinforced  Con- 
crete Platform,  Barge  Canal,  Schnectady,  N.  Y. 

which  the  platform  takes  only  a  small  portion  of  the  thrust, 
is  shown  in  Fig.  43. x  This  type  of  wall  was  designed  to 
retain  the  filling  in  large  solid  piers.  The  walls  were  all 
built  far  out  from  the  shore  on  a  hard  sand  and  gravel 
bottom  overlaid  with  mud.  The  sheet  piling  was  first 
driven  and  then  the  slips  between  the  piers  dredged  out, 
leaving  a  sloping  bank  of  sand  outside  the  sheet  piling  for 

1  "Wharves  and  Piers,"  E.  P.  Goodrich.    Trans.  Am.  Soc.  C.  E.,  Vol.  LIV, 
part  I,  p.  26. 


RETAINING   WALLS 


87 


the  width  of  the  platform.  The  sheet  piling  was  tied  with 
rods  extending  across  the  pier  and  a  bank  of  riprap  was 
placed  to  protect  the  slope  against  erosion  and  to  aid  in  sup- 
porting the  sheet  piling.  The  wooden  pile  platform  was  then 
built  with  a  wale  against  the  top  of  the  sheet  piling.  A 


;3xlO  "Yellow  HI  H/ftr/f  fa 
Pine  Brace 


Fig.  40.     Platform  Wall,  Barge  Canal,  Whitehall,  N.  Y. 

portion  of  the  wall  was  injured  by  a  fire,  and  the  sheet 
piling  and  side  system  of  the  piers  had  to  be  extensively 
repaired,  on  account  of  decay,  after  twelve  or  fifteen  years' 
service.  It  is  claimed,  however,  that  the  first  cost  of  the 
construction  was  very  low. 

A  similar  wall  was  built  in  1914,  at  Los  Angeles,  Cal.,  in 
which  all  the  piles  were  creosoted.  . 


88  WHARVES  AND  PIERS 

One  of  the  most  remarkable  sea  or  bulkhead  walls  is  that 
constructed  by  the  Department  of  Docks,  in  New  York 
City,  which  in  some  places  is  built  in  mud  170  feet  deep. 
It  is  of  the  relieving  platform  type,  supported  on  piles, 
which  do  not  extend  through  the  mud  to  hard  bottom, 
with  a  vertical  facing  of  concrete  blocks  extending  17  feet 
below  low  water.  This  wall,  as  originally  designed  in  1876, 
is  shown  in  Fig.  44.  The  mud  was  dredged  for  a  width 
of  about  85  feet  to  a  depth  of  30  feet,  more  or  less,  depend- 


Section    c-D 
Fig.  41.     Sloping  Platform  Wall,  Savannah,  Ga. 

ing  on  the  consistency.  A  layer  of  small,  smooth  cobble 
or  gravel  was  then  deposited  to  prevent  the  mud  flowing 
into  the  trench,  the  piles  driven,  straightened,  and  stay- 
lathed.  Guide  logs  were  sunk  between  the  longitudinal 
rows  to  aid  the  accurate  alignment  of  the  piles.  Cobbles 
and  riprap  were  deposited  up  to  18  feet  below  mean  low 
water,  cobbles  being  used  between  the  piles,  as  they  make 
a  more  compact  filling  than  the  angular  riprap  stone.  A 
binding  frame,  in  sections  24  feet  long,  was  next  slipped 
over  the  transverse  rows  of  piles  and  sunk  to  the  top  of  the 
bank  of  cobble  by  means  of  weights.  Divers  spiked  it  in 


RETAINING  WALLS 


89 


place  and  filled  the  spaces  between  the  longitudinal  tim- 
bers in  front  and  rear  and  the  piles  adjacent  to  them  with 
wedges.     The  object  of  this  binding  frame  was  to  prevent 
the  possible  pushing  out  of  the 
front  row  of   piles   from  under 
the  concrete  blocks,  which  were 
only  7  feet  wide  on  the  bottom. 
The  piles  were  then  cut  off  with 
a  circular   saw   mounted   on   a 
scow. 

As  it  is  impossible  to  space 
piles  in  actual  practice  with 
great  accuracy,  and  as  it  was 
essential  that  the  piles  should 
all  perform  their  full  duty,  it 
was  necessary  to  ascertain  ac-  Fig<  42-  sl°Ping  Platform  Wall, 

f    .,          .,  Rio  Janeiro. 

curately  the  location  of  the  pile 

heads.  For  this  purpose  a  wire  screen,  having  ten  meshes 
to  the  foot  with  a  frame  heavy  enough  to  sink,  was  lowered 
by  means  of  a  derrick  to  the  tops  of  the  piles  on  which 

- /50'-0" - 


Fig.  43.     Platform  Walls,  Bush  Terminal,  Brooklyn,  N.  Y. 

the  blocks  were  to  rest.  A  diver  then  marked  the  position 
of  each  pile  by  means  of  snap  hooks  which  he  attached  to 
the  wires  of  the  screen.  The  screen  was  then  raised  and 
the  location  of  the  pile  heads  plotted.  If  any  piles  were 
found  which  were  outside  the  limits  of  the  base  of  the 


90 


WHARVES  AND  PIERS 


concrete  blocks,  or  if  they  were  too  unevenly  distributed, 
extra  ones  were  driven. 

It  was  impracticable  to  cut  off  all  the  piles  at  exactly 
the  same  level,  and  a  novel  means  was  adopted  for  insuring 
a  uniform  bearing  of  the  block  on  all  the  piles.  A  weighted 
wooden  frame  larger  than  the  base  of  the  concrete  blocks 
was  covered  with  a  network  of  small  rope.  On  the  net- 
work was  placed  a  bag  or  mattress  consisting  of  two  sheets 


Mean  High  Wafer I|Bs?3?!         £ 


Fig.  44.     Bulkhead  Wall  with  Relieving  Platform  Type  of  1876,  Dept.  of 
Docks,  New  York,  N.  Y. 

of  burlap  filled  with  a  layer  of  1 :  2  mortar,  made  with  slow- 
setting  cement,  mixed  to  a  stiff  paste.  When  the  concrete 
block  was  ready  for  setting,  the  mattress,  filled  with  the 
freshly  mixed  mortar,  was  lowered  to  the  tops  of  the  piles 
and  adjusted  by  a  diver,  who  cut  the  rope  netting  around 
the  edges  of  the  frame.  The  frame  was  then  raised  and 
the  concrete  block  immediately  set  on  top  of  the  mattress. 
Portions  of  the  wall  when  removed,  subsequently,  showed 
the  complete  success  of  this  device.  The  heads  of  the  piles 
pushed  into  the  soft  mortar  until  the  unit  pressure  was 
uniform  and  the  mortar  was  found  to  be  hard  and  sound. 


RETAINING   WALLS 


91 


The  blocks  were  made  of  a  comparatively  dry  mixture 
of  1 :  2 :  5  concrete,  mixed  by  hand  and  thoroughly  tamped 
and  cured.  They  weighed  about  70  tons,  and  were  placed 
with  a  100-ton  capacity  floating  derrick  owned  by  the  de- 
partment. The  durability  in  sea  water  of  these  concrete 


M.L.W. 


Bracing  Piles 
"  6'csoC. 


Vertical  Piles 
•C--J'  C.  foC. 


Fig.  45.     Details  of  Fig.  44. 

blocks,  which  do  not  extend  above  mean  low  tide  and  are 
not  subject  to  the  action  of  frost,  has  been  referred  to  in  a 
previous  chapter.  Above  low  water  the  masonry  wall  is 
of-  mass  concrete  faced  with  heavy,  accurately  jointed, 
granite  ashlar. 

Back  of  the  masonry  portion  of  the  wall  the  spaces  be- 
tween the  piles  were  filled  with  cobble,  the  platform  laid, 
and  the  riprap  embankment  completed  as  shown. 


92 


WHARVES   AND  PIERS 


An  extraordinary  feature  of  this  wall  is  that  no  metal 
is  used  in  its  construction;  all  fastenings  of  piles,  binding 
frames,  caps  and  planking  being  of  oak  or  locust  treenails 
up  to  3  inches  in  diameter,  as  shown  in  Fig.  46. 

The  economy  of  this  design,  due  to  the  small  amount  of 
expensive  concrete  in  proportion  to  the  size  of  the  structure, 
deserves  special  attention. 

This  wall  settles  considerably,  but  does  not  move  laterally 
to  any  great  extent,  notwithstanding  the  heavy  pressure 
if^t  exerted  on  it.     The  maxi- 

mum settlement  has  been 
about  4  feet  and  the  maxi- 
mum deviation  from  line 
about  6  inches.  The  move- 
ment is  comparatively  rapid 
for  the  first  two  or  three 
years  and  then  diminishes 
to  something  less  than  an 
inch  a  year.  Movements  of 
over  one  or  two  feet  oc- 
curred only  in  a  few  short 

Fig.  46.      Detail   of   Pile   Connections    sections  and  the   settlement 
showing  Wooden  Treenail  Fastenings.  . 

greater    portion 


in  the 


of 

several  miles  of  wall  has  been  only  a  few  inches.  The 
settlement  is  corrected  by  building  up  the  granite  face 
on  the  wall  from  time  to  time  and  by  raising  the  decks 
on  the  inner  ends  of  the  piers  which  sink  with  it.  The 
extraordinary  method  of  construction  of  this  wall  caused 
some  criticism,  and  in  1896  a  board  of  engineers  reported 
as  follows: 

"  To  float  a  wall  in  mud  when  the  wall  must  also  take  a  horizontal 
thrust  is  a  problem  which  can  only  be  solved  by  care  and  experience, 
no  formulas  or  mathematical  rules  being  available.  The  wall,  as  now 
built,  is  a  satisfactory  solution  of  the  problem.  .  .  ." 

There  was  no  modification  in  the  design  of  this  wall, 
except  the  raising  of  the  platform  one  foot  above  low  water 
to  increase  the  rapidity  of  construction,  until  1899,  when, 


RETAINING  WALLS 


93 


owing  to  decrease  in  the  price  of  cement  and  increase  in 
that  of  labor  and  lumber  it  was  redesigned  in  order  to 
lessen  the  cost.  For  this  purpose  the  blocks  were  widened 
to  10^  feet  on  the  bottom,  resting  on  four  rows  of  piles  in- 
stead of  three,  the  binding  frame  and  half  of  the  bracing 


\ ;"; 

Foundation  and  Platform  P//es  Spaced  4  Ft  C.  toC. 
longitudinally,  except  in  Front  Row,  which  are  spaced.  2  Ft  CtoC. 

Fig.  47.     Bulkhead  Wall  with  Relieving  Platform,  Type  of  1899,  Dept.  of 
Docks,  New  York,  N.  Y. 

piles  were  omitted,  and  the  amount  of  riprap  and  granite 
decreased. 

Where  this  wall  is  built  on  hard  bottom,  but  where  rock 
is  below  the  reach  of  piles  of  ordinary  length,  a  relieving 
platform  of  concrete  deposited  under  water  instead  of  a 
timber  platform  has  been  used,  as  shown  in  Fig.  48.  This 
design  calls  for  less  concrete  than  that  shown  in  Fig.  21. 
A  similar  design  for  localities  where  the  rock  is  located  at 
such  depths  that  a  gravity  wall  is  too  expensive  is  shown  in 


94 


WHARVES  AND  PIERS 


Fig.  49.    The  use  of  bracing  piles  counteracts  any  tendency 
to  move  outward. 

A  relieving  platform  wall,  with  sheet-pile  facing  sur- 
rounding a  solid-filled  pier,  3000  feet  long  by  292  feet  wide, 
at  Chicago,  111.,  is  shown  in  Fig.  50.  In  this  wall,  which 
was  built  in  water  from  20  to  27  feet  deep,  the  usual  timber 
platform  at  low-water  level  and  the  gravity  wall  on  the 
outer  edge  of  it  were  combined  in  one  structure  of  reinforced 


Fig..  48.  Platform  Wall,  East  23rd  St.,  New  York,  N.Y. 

concrete,  18^  feet  wide.  The  platform  is  supported  by 
three  rows  of  round  piling  and  a  row  of  12-inch  triple-lap 
wooden  sheet  piling.  The  three  rows  of  round  piles  are 
tied  together  with  rods  located  2|  feet  below  the  water 
surface.  Riprap  was  deposited  outside  of  the  sheeting  to 
as  great  a  height  as  possible  without  interfering  with  vessels 
mooring  alongside.  The  outer  rows  of  piles  are  spaced  4 
feet  apart  and  the  interior  rows  2  feet.  In  the  outer  portion 
of  the  pier  there  are  tie  rods  extending  from  wall  to  wall. 
Three  rows  of  wales  give  a  bearing  for  the  sheet  piling 


RETAINING   WALLS 


95 


against  the  outer  row  of  round  piles,  the  lower  wale  or 
mud  sill  being  of  reinforced  concrete.  The  piles  were  cut 
off  about  one  foot  above  the  normal  water  level  and  the 
space  between  them  was  filled  with  riprap  from  the  Chicago 
Drainage  Canal,  up  to  the  surface  of  the  water.  The  area 
enclosed  by  the  wall  was  filled  partly  by  dipper  and  partly 
by  hydraulic  dredges.  A  sheet  of  canvas  was  placed  on 


Fig.  49.     Platform  Wall,  Rector  St.,  New  York,  N.  Y. 

top  of  the  riprap  to  prevent  the  concrete  from  leaking  into 
the  voids  and  from  being  washed  out  and  the  concrete  wall 
built  to  1\  feet  above  the  water  level. 

The  relieving  platform  in  this  wall  supports  the  outer 
edge  of  a  reinforced  concrete  freight  deck  designed  for  the 
very  low  load  of  only  250  pounds  per  square  foot,  together 
with  the  columns  of  a  passenger  platform  with  a  live  load 
of  200  pounds.  The  thrust  against  the  sheet  piling  is 
diminished  by  the  bank  of  riprap. 


96 


WHARVES  AND  PIERS 


This  wall  was  criticised  because  it  bulged  with  a  maximum 
deviation  from  line  of  18  inches,  but  it  was  decided  by  a 
board  of  engineers  that  the  deformation  of  the  sheet  pile 


Cast  iron  mooring  K- £>'-— «n  ,;  /- _r  / 

££f  e/e/y  tfWrt-***  /£"  J  ! !    ^/^^  ^^  f^^ 


Fender,.... 

m 


Anchor 
Rod 


Fig.  50.     Wall  of  Wooden  Sheet  Piling  with  Concrete 
Platform,  Municipal  Pier,  Chicago,  111. 

and  concrete  walls  affected  the  appearance  only  and  not 
the  safety  of  the  structure. 

The  boring  of  -the  horizontal  holes  in  the  piles  2|  feet 
below  the  surface  of  the  water  where  the  waves  were  often 
high  and  troublesome  and  the  placing  of  the  rods  in  the 
holes  were  accomplished  by  an  ingenious  device.  Augers, 
driven  by  means  of  pneumatic  boring  machines,  were 


RETAINING   WALLS 


97 


El.  ZSI.O 


mounted   in  guides  in  a  wooden  frame  which  was    sus- 
pended from  guide   timbers.      The  boring  machines  were 
arranged  so  that  when  the  guide  frame  was  in  place  they 
were    above    the   water 
and  were   connected  to 
the    augers   by    inclined 
shafts      and      universal 
joints.      The     tie     rods 
were  placed  by  men  clad 
in     watertight      rubber 
suits  standing  on  a  sub- 
merged raft. 

A     design    somewhat 
similar  to  the  foregoing, 

e/rce/yect  hot 

in  which  steel-sheet  pil- 
ing instead  of  wood  is 
used,  is  illustrated  in 
Fig.  51.  In  this  case 
the  relieving  platform  is 
only  about  8  feet  wide 
for  16  feet  depth  of  water  and  the  principal  portion  of 
the  thrust  is  taken  by  the  tie  rods  and  anchor  piles.  The 
small  area  of  the  steel  beam  in  rear  of  these  anchor 
piles  and  the  absence  of  bracing  piles  in  the  anchorage  is 
noticeable. 

Another  design  for  a  coal-loading  wharf  at  Toledo,  O., 
in  which  bracing  piles  are  used  to  take  some  of  the  thrust, 
is  shown  in  Fig.  52.  This  wall  was  built  outside  of  an  old 
one  and  the  work  was  done  in  the  winter  when  navigation 
was  closed. 

A  relieving  platform  wall  of  reinforced  concrete  for  an 
ore  dock  at  Detroit,  Mich.,  is  illustrated  in  Fig.  53.  The 
filling  is  retained  by  a  low  sheet-pile  bulkhead  behind 
a  reinforced  concrete  platform  36  feet  wide  on  oak  piles, 
over  the  natural  sloping  bank  of  the  river,  without  riprap 
or  other  revetment.  The  depth  of  water  at  the  edge  of  the 
deck  was  about  15  feet.  The  platform,  not  being  intended 


/2'Chan 
2  Die,  Tit  Rod 
Spacing  10-0  "c.  foe 


98 


WHARVES  AND  PIERS 


for  the  landing  of  freight,  was  designed  for  a  load  of  only 
100  pounds  per  square  foot.  The  heavy,  longitudinal 
girders  carry  tracks  for  an  ore  unloading  machine,  the 
main  tower  of  which  spans  the  platform.  The  relieving 
platform  carries  a  railroad  track  and  the  ore  floor,  the 
portion  under  the  latter  being  designed  to  carry  6800 
pounds  per  square  foot.  The  piles  were  cut  off  3  inches 
above  the  water  line  and  the  concrete  girders  extend  6 
inches  below  it.  The  fendering  system  consists  of  a  line 
of  spring  piles  and  an  oak  fender  on  the  outer  edge  of  the 
platform  slab.  Patents  on  the  general  feature 3  of  this 

Blocks,  so' c.  toe. 

Key.at  Expansbn 
'~'~te,  every  SO' 


Elevation 
Fig.  52.  Wall  with  Wooden  Sheet  Piles  and  Concrete  Platform,  Toledo,  O. 

wall  are  held  by  S.  D.  Carey,  Cleveland,  O.  A  somewhat 
similar  wall,  constructed  at  Cleveland  under  the  same 
patents  is  shown  in  Fig.  54. 

Another  wall  of  similar  type  for  an  ore  dock  at  Cleveland, 
is  shown  in  Fig.  55.  The  piles  under  the  wall,  except  those 
in  the  front  and  rear  rows,  were  cut  off  at  mean  low  water. 
The  anchorage  consisted  of  old  rails  which,  together  with 
the  tie  rods,  were  entirely  buried  in  concrete  to  prevent 
any  possible  corrosion.  Oak  piles  were  used  throughout. 
This  wall  had  to  support  heavy  heaps  of  ore  immediately 
in  the  rear  of  the  platform. 

A  novel  method  of  capping  piles,  cut  off  below  low-water 
level,  was  used  at  Hamilton,  Ont.,  on  a  wall  built  with  a 
narrow  relieving  platform  supported  by  transverse,  braced 


RETAINING   WALLS 


99 


100 


WHARVES  AND  PIERS 


pile  bents,  which  also  afford  lateral  support  to  sheet  piling, 
as  illustrated  in  Fig.  56.  This  wall  was  built  out  in  the 
water  at  some  distance  from  the  natural  shore  line.  The 

work    of    capping    and 


Fig.  54.     Platform  Wall,  Cleveland,  O. 


bracing  the  piles  is  usu- 
ally performed  by  divers 
and  is  slow  and  expen- 
sive, particularly  where 
the  water  is  rendered 
turbid  by  sewage  or 
other  causes.  In  this 
case  a  floating  caisson 
or  diving  bell  was  used 
to  cap  the  piles,  which 
were  driven  down  some 
two  feet  below  low  lake 
level  and  cut  off  at  three 


feet  below  that  elevation.     The  water  was  depressed  to  a 
depth  of  about  6  feet,  and  the  air  pressure  was  therefore 


Fig.  55.     Platform  Wall  with  Wooden  Sheet  Piling,  Cleveland,  O. 

only  about  3  pounds  per  square  inch.  The  longitudinal 
alignment  of  the  piles  was  effected  by  timber  clamps, 
placed  below  the  caps  and  tightened  by  wire  ropes, 
operated  by  a  hoisting  engine,  as  shown  in  the  illustra- 


RETAINING    WALLS 


101 


tions.  Steel-sheet  piling  at  the  face  of  the  wall  was  used 
to  retain  the  filling.  An  interesting  comparison  could  be 
made  between  this  design  and  one  in  which  the  horizontal 
thrust  is  taken  by  bracing  piles  instead  of  by  the  plank 
braces  put  in  place  by  divers. 

A  design  for  a  relieving  platform  wall  at  Jacksonville,  Fla., 
with  a  vertical  facing  of  steel-sheet  piling  is  illustrated  in 


~-ftjl!ey^ 


- PjJ  '-Pile  alignment       Hois t 
clamp  timbers 

Lackawanna  steel 


Ready  for  Work 

£ 


Dredged-, 
E/.227.S  —Y- 


>,-lk"diam.botf,3!6"la.. 
.Finished  Pile  Benf 


V 


Pitetenf 
at  I  I  ft. 
"centers 


3C— 


-  3'J<-  3'  J, .3!j<..r/(6?..  J 


SECTION  THROUGH  FINISHED  WALL 
SHOWING  (DOTTED)  LONGITUDINAL 

SECTION  OF  CAISSON 


Plan 
Fig.  56.     Method  of  Capping  Piles  for  Platforms,  Hamilton,  Ont. 


Figs.  57  and  58.  The  sheet  piling  is  supported  by  I  beams 
driven  into  the  shell  rock  of  the  bottom  and  is  protected 
from  corrosion  by  concrete  deposited  by  means  of  a  tremie. 
The  I  beams  are  spaced  4  feet  apart  and  are  tied  at  low- 
water  level  to  inclined  pile  anchors  located  39  feet  in  rear 
of  the  face  of  the  bulkhead.  The  timber  relieving  platform 
is  18  feet  wide  and  is  designed  to  carry  a  live  load  of  only 
200  pounds  per  square  foot  in  addition  to  the  weight  of 
the  filling.  This  platform  reduces  the  thrust  on  the  sheet 


10.2  WHA&VES  AND  PIERS 

piles  and  tie  rods  to  the  sum  of  that  of  the  filling  above  the 
platform  and  that  of  the  pressure  wedge  below  the  platform, 


Fig.  57.     Platform  Wall,  Jacksonville,  Fla. 


E  e  S+ee/  Sheef  ft/ing 


Fig.  58.    Horizontal  Section  of  Fig.  57. 

which  is  diminished  by  the  resistance  of  the  platform  piles. 
This  wall  is  planned  for  a  depth  of  water  of  30  feet  below 
mean  low  tide  and  a  height  of  only  4  feet  above  it. 


EETAINING   WALLS  103 

SHEET-PILE  WALLS 

Sheet-pile  walls,  for  purposes  of  classification,  may  be 
defined  as  those  in  which  the  material  behind  the  wall  is 
retained  by  a  row  of  sheet  piling,  supported  against  the 
pressure  of  the  filling  by  the  resistance  of  the  material  into 
which  the  piles  are  driven,  and  by  tie  rods  running  back  to 
anchors  of  various  patterns  embedded  in  the  earth  in  the 
rear,  or  by  bracing  piles  in  front.  Those  in  which  sheet 
piling  is  used  in  conjunction  with  a  platform  have  been 
classified  as  platform  walls.  The  great  advantage  of  sheet- 
pile  walls  lies  in  their  cheapness,  simplicity,  and  the  ease 
and  rapidity  with  which  they  may  be  constructed.  Those 
that  are  of  timber  decay  above  water  in  a  few  years  and 
then  have  to  be  torn  out  and  rebuilt  or  repaired  by  driving 
another  row  of  sheet  piling  outside  the  old  one.  In  many 
cases  the  latter  method  is  impossible,  owing  to  the  restric- 
tions of  the  harbor  authorities,  property  lines,  and  to  the 
undesir ability  of  narrowing  slips  and  waterways.  Because 
of  its  lack  of  durability  and  the  cost  of  rebuilding,  the  use  of 
wooden  sheet-pile  walls  for  important  structures  has  of  late 
years  been  abandoned  in  favor  of  those  of  concrete  or 
steel,  or  of  those  in  which  a  relieving  platform  is  used. 
The  use  of  unprotected  steel-sheet  piling  in  fresh  water  has 
increased  greatly  in  the  last  few  years. 

Sheet-pile  walls  are  especially  suited  to  places  where  it  is 
necessary  to  build  a  wall  close  to  existing  structures. 

The  reliability  of  this  type  of  wall  depends  largely  on  the 
nature  of  the  support  for  the  upper  portion  of  the  piling. 
For  this  purpose  nothing  can  compare  with  bracing  piles, 
and  anchors  for  tie  rods  of  which  bracing  piles  do  not  form 
a  part  are,  in  many  cases,  most  objectionable  on  account 
of  the  uncertainty  of  the  horizontal  compressibility  of  the 
material  in  which  they  are  placed  or  of  its  safe  angle  of 
repose. 

One  of  the  simplest  forms  of  wooden  sheet-pile  bulkhead 
was  used  for  many  years  in  Chicago  and  is  shown  in  Fig. 


104 


WHARVES  AND  PIERS 


59.  A  row  of  round  piles  was  driven  along  the  bulkhead 
line,  a  mud  sill  and  two  or  more  wales  placed  in  the  rear  of 
these,  and  sheet  piling  driven  against  the  sills  and  wales. 
The  round  piles  were  tied  with  rods  to  deadmen  in  the 
rear  of  the  wall.  For  temporary  structures,  requiring  no 
very  great  depth  of  water,  in  the  firm,  tenacious  clay  of 
the  Chicago  district,  this  design  is  sufficiently  good.  It  is 
also  exceedingly  cheap. 

A  simple  form  of  steel-sheet  pile  wall  was  used  for  the 


EL3&M 


[£] 


El.  -1-2.0 


El.  00 


1.  -10. 


Fig.  59.     Sheet-pile  Wall,  Chicago,  111. 

approach  to  the  ship  lock  at  Blackrock,  Buffalo,  N.  Y.,  and 
is  shown  in  Fig.  60.  In  this  case  the  required  depth  of 
water  was  23  feet.  A  row  of  painted,  interlocking  steel- 
sheet  piling  of  the  arched  form,  which  gives  a  very  high 
bending  moment,  was  driven  10  feet  below  the  bottom  of 
the  canal  and  tied  back  to  a  pile  and  wooden  beam  anchor- 
age, with  rods  placed  some  2  feet  above  mean  lake  level 
but  above  the  water  surface  at  the  time  they  were  placed. 
Two  lines  of  wooden  wales  or  fender  timbers  completed  the 
structure.  This  wall  acts  simply  as  a  retaining  wall  on 


RETAINING    WALLS 


105 


the  approach  to  a  canal  lock,  and  does  not  have  to  carry 
any  great  surcharge  of  freight  or  other  live  load.  Bracing 
piles  were  not  used  in  the  anchorage. 

A  steel-sheet  pile  wall,  founded  on  rock,  was  built  for  a 
coal  pier  for  the  Pennsylvania  lines  at  Sandusky,  Ohio. 
The  sheet  piling  is  supported  by  reinforced  concrete  piles 
spaced  8  feet,  9  inches,  apart,  dowelled  to  the  rock  with 
old  car  axles.  The  concrete  piles  and  the  steel-sheet  piles 
are  embedded  in  the  bottom  of  a  light,  concrete  gravity 
wall,  8  feet  high,  extending  one  foot  below  mean  lake  level. 
At  the  middle  of  the 
panel  between  the  ^tg^^ 

.,  .  4^    */„„,  kv/ 

concrete  piles,  pairs 
of  2-inch  rods  are 
attached  to  the  heads 
of  the  steel-sheet 
piling  with  washers 
made  of  old  rails  and 
are  fastened,  at  the 
opposite  side  of  the 
pier,  to  an  old  dock 
wall.  The  rods  are 
encased  in  concrete 


E/.-33.O 


Fig.  60.     Steel-sheet  Pile  Wall,  Black  Rock, 
Buffalo,  N.  Y. 


to  prevent  any  possible  corrosion.  The  piles  are  octagonal 
in  section  and  18  inches  in  diameter.  They  are  reinforced 
with  vertical  rods  and  hooping  and  have  moulded  into  them 
the  two  halves  of  a  split  sheet  pile  and  a  6-inch  pipe. 
Through  the  pipe  the  hole  for  the  dowel  was  drilled  into 
the  rock  after  the  pile  was  in  place  and  the  car  axle 
then  dropped  down  through  the  pipe  and  grouted  into 
the  rock.  There  were  18  feet  of  water  over  the  rock  at  this 
pier.  Fig.  61  shows  the  construction. 

Another  wall  of  extraordinary  height  founded  on  rock, 
though  not  strictly  a  sheet-pile  wall  because  the  sheeting 
is  horizontal  instead  of  vertical,  was  built  for  the  same 
railroad  at  Ashtabula  Harbor,  Ohio,  and  is  shown  in  Fig. 
62.  The  channel  bottom  in  this  case  was  23  feet  below 


106 


WHARVES  AND  PIERS 


mean  low  water  and  the  wall  had  to  support  one  side  of  a 
fill  about  62  feet  wide,  carrying  four  standard  tracks  for 
heavy  coal  cars,  at  an  elevation  of  17  feet  above  mean  lake 
level.  The  posts  in  this  case  were  made  of  two  18-inch  I 
beams,  spaced  7J  feet  apart,  extending  into  the  rock  4  feet 
and  tied  to  concrete  deadmen  at  the  opposite  side  of  the 
high  fill  with  2J-inch  rods.  Horizontal  sheeting  of  6-inch 
by  12-inch  lumber  was  placed  behind  the  posts,  from  the 
rock  to  18  inches  below  mean  lake  level  and  above  the 


Anchor  f?oc/3,-  -  • 
encased  in 
Concrefa 


Fig.  61.     Steel-sheet  Pile  Wall,  Sandusky,  O. 

wooden  sheeting  reinforced  concrete  slabs  6  inches  thick, 
cast  in  place,  were  used.  At  the  bottom  of  the  wooden 
sheeting  bags  of  mortar  were  placed  to  make  a  seal  to 
prevent  the  filling  from  washing  out.  The  holes  for  the 
posts  were  24  inches  in  diameter  and  were  drilled  with  a 
large  steam  drill  with  a  special  form  of  bit.  The  space 
between  the  posts  and  the  sides  of  the  holes  was  filled  with 
concrete,  which  was  sent  down  in  bags  to  divers,  who  opened 
the  bags  and  placed  the  concrete  in  position. 

The  rock  behind  this  wall  extended  up  nearly  to  the 
water  line,  so  that  the  thrust  of  the  filling  was  much  less 


RETAINING    WALLS 


107 


than  it  would  have  been  if  the  rock  behind  the  wall  had 
been  at  the  same  elevation  as  in  front. 

This  design  was  considered  superior  to  that  of  an  adjacent 

stO'x/8'W.O.  Timber 

' ..-Sj* Washers  Back  to  Back 


Water  Line, 


Cross    Section. 


Side     Elevotion. 


Fig.  62.     Wall  of  Steel  Posts  with  Wooden  Sheathing,  Ashtabula,  O. 

wall  in  which  vertical  sheeting  was  used,  in  that  it  did  not 
require  any  horizontal  wales  below  the  water  line,  the 
placing  of  which  was  somewhat  difficult. 


108 


WHARVES  AND  PIERS 


Another  steel-sheet  pile  wall  was  built  for  a  terminal  or 
freight  warf  on  the  summit  level  of  the  Barge  Canal  at 
Rome,  N.  Y.  (See  Fig.  63.)  In  this  case  the  portion  ex- 
tending from  the  top  to  2  feet  below  the  normal  water  level 
was  encased  in  concrete  which  was  bounded  to  the  sheet 

piling  with  steel  bars.  A 
continuous  anchorage  beam 
of  reinforced  concrete  was 
provided  and  the  tie  rods  were 
encased  in  concrete  to  prevent 
corrosion.  The  only  portion 
of  this  wall  exposed  to  rust 
is  the  outer  face  of  the  sheet 
piling  the  heads  of  the  tie 
rods  and  the  steel  wales 
through  which  the  rods 
project.  These  can  be  ex- 
amined and  painted  if  neces- 
sary, as  the  water  can  be 
drawn  from  the  canal  in  the 
winter  time  when  navigation 
is  closed.  There  was  a  con- 
siderable saving  in  the  exca- 
vation in  this  type  of  wall 
over  the  platform  type.  The 
channel  in  front  was  excavated 
after  the  wall  was  completed. 
A  reinforced  concrete  sheet- 
Fig.  63.  Steel-sheet  Pile  Wall  Barge  pjle  wall  illustrated  in  Fig. 

Pannl     T?nmp    N    V  i 

64  has  been  built  to  enclose 

several  large  solid-filled  piers  in  Baltimore.  The  previous 
type  of  wall  consisted  of  wooden  sheet  piling  with  a 
wooden  platform  on  piles  having  a  stone  masonry  wall  on 
its  outer  edge;  but  the  prospect  that  the  teredo,  which 
had  been  driven  from  the  vicinity  by  sewage,  might 
return  after  the  construction  of  a  sewage-disposal  plant 
which  was  under  consideration,  together  with  the  fact 


RETAINING   WALLS 


109 


that  the  type  of  wall  in  use  required  a  large  amount  of 

dredging,  made  it  appear  advisable  to  build  a  wall  entirely 

of  concrete  and  steel.    Steel  cylinders  with  parallel  sides  and 

semicircular  ends,  10  feet  long,  3  feet  wide,  and  about  29 

feet  high,  were  sunk  25  feet  apart  to  a  hard  gravel  bottom 

approximately   22   feet   below   low   water.     The   cylinders 

were  tied  across  the  pier  to  those  on  the  opposite  side,  or, 

whenever  the  distance  was  too  great  or  buildings  interfered, 

to    concrete    deadmen.     Passing    through    the    cylinders, 

above  the  water  line,  were  horizontal 

steel  lattice  girders  wrapped  with  wire 

mesh  and  encased  in  concrete.     Back 

of    these    girders,    reinforced   concrete 

sheet  piles,  12  inches  by  18  inches  in 

section,  were  driven  with  their  heads 

bearing  against  the  girders.     Another 

steel  girder,  encased  in   concrete,  was 

placed  on  top  of  the  cylinders  at  the 

front  edge  and  supported  one  side  of 

a   reinforced    concrete    slab,    the  rear 

of  which  rested  on  a  reinforced  con- 

crete wall  built  on   top  of  the  sheet 

.,.  ,-..         ,   ,  .  ,,, 

piling.      This   slab   carried    a  .  cobble- 

stone pavement  and  on  its  front  edge  a  concrete   curb. 

The  steel  cylinders  were  sunk  in  a  trench,  dredged  to  15 
feet  depth,  by  jetting  and  driving  with  a  steam  hammer 
mounted  in  a  specially  constructed  steel  frame  resting  on 
top  of  the  cylinders.  Some  of  these  were  put  in  place 
without  much  difficulty,  but  many  obstructions,  such  as 
old  wooden  sheet  piling,  cast-iron  pipes,  lumps  of  brick 
masonry  and  logs,  were  encountered.  These  had  to  be 
removed  by  divers  or  by  men  working  from  the  inside  of 
the  cylinders,  where  it  was  possible  to  keep  the  water  down 
by  pumping.  The  narrowness  of  the  cylinders  made  such 
work  extremely  difficult. 

The  concrete  sheet  piles  were  not  grooved  or  dovetailed 
and  were  bevelled  in  one  direction  to  make  them  drive 


?f  ;  „  Concrete  Sheet- 

pile  Wall,  Baltimore,  Md. 


110 


WHARVES  AND  PIERS 


close  together.  They  were  driven  by  jetting  and  steam 
hammers.  It  was  not  always  possible,  however,  to  make 
them  fit  closely,  and  in  some  cases  narrow  piles  were  driven 
in  the  interstices,  and  in  others  additional  piles  were  driven 
in  the  rear  of  the  gaps. 

This  wall  is  said  to  have  cost  only  $58.00  a  linear  foot 
exclusive  of  dredging  and  $87.00  inclusive  of  dredging. 


^  1  1  1 

jii  i 
iii  i 

Tie  3  Spaced  20  ~0  "C  fo  C 

Fig.  65.     Concrete  Sheet-pile  Wall,  Raymond 
Patent,  Barge  Canal,  Albany,  N.  Y. 

A  sheet-pile  wall  entirely  of  reinforced  concrete  has  been 
designed  and  successfully  built,  in  many  places,  by  the 
Raymond  Concrete  Pile  Co.  Some  of  the  features  are 
patented.  This  wall  consists  of  a  line  of  reinforced  concrete 
sheet  piles  with  their  heads  supported  by  a  horizontal 
girder,  located  above  the  water  line,  which  rests  on  a  row 
of  concrete  bearing  piles  some  three  or  four  feet  in  front 
of  the  sheet  piles.  The  girder  carries  a  vertical  facing  wall 
which  is  held  against  the  overturning  forces  by  buttresses 


RETAINING    WALLS  111 

supported  on  a  row  of  piles  in  the  rear.  The  whole  struc- 
ture is  tied  back  to  concrete  deadmen.  This  design,  though 
expensive  in  comparison  with  other  types,  is  efficient  where 
it  is  absolutely  necessary  to  use  concrete  for  the  whole 
structure,  but  rather  extravagant  in  the  use  of  concrete 
for  ties  and  anchor  piles.  The  use  of  concrete  for  this 
purpose  is  justified,  however,  in  some  non- tidal  waters 
where  the  anchor  piles  cannot  be  cut  off  low  enough  to 
ensure  their  safety  from  decay.  A  wall  of  this  type  at  the 
Barge  Canal  Terminal  at  Albany,  N.  Y.,  is  shown  in  Fig.  65. 


CHAPTER  V 
PIERS 

COMPARISON  OF  TYPES 

OF  the  three  types  of  piers  —  pile-platform,  block-and- 
bridge,  and  solid-fill  —  the  first  is  usually  the  most  ad- 
vantageous in  localities  where  the  water  is  not  too  deep 
and  the  bottom  is  suitable  for  piles.  It  offers  less  obstruc- 
tion to  the  free  flow  of  water,  sewage,  and  ice,  does  not 
materially  affect  the  tidal  prism,  may  be  rapidly  constructed, 
and  may  be  readily  altered,  removed,  or  enlarged.  In  piers 
of  ordinary  proportions  of  length  to  breadth,  where  marine 
borers  are  not  active,  it  is  usually  cheaper  than  the  filled-in 
type. 

The  block-and-bridge  model  is  rather  limited  in  its  applica- 
tion, as  it  is  economical  only  for  small  piers  in  shallow  water 
and  on  hard  bottom.  It  has  the  advantage  that  if  the 
blocks  are  of  cribwork  it  may  be  built  without  the  use  of 
expensive  equipment,  such  as  pile  drivers  and  floating 
derricks. 

The  solid-filled  type  of  pier  may  be  used  where  the  ob- 
struction to  the  flow  of  the  water,  sewage,  and  ice  and  the 
diminution  of  the  tidal  prism  are  not  serious  objections. 
It  has  been  urged  that  a  large  vessel  lying  alongside  a 
pile  pier  offers  nearly  as  much  obstruction  to  the  flow  of 
water  as  a  solid-filled  pier,  but  it  is  to  be  remembered  that 
in  tidal  waters  the  bottom  of  the  ship  is  near  the  bottom 
of  the  slip  only  a  portion  of  the  time  and  that  for  some 
portions  of  the  time,  parts  of  the  pier  are  not  obstructed 
by  ships,  thus  permitting  the  flotsam,  ice,  etc.,  which 
accumulate  in  a  slip  to  pass  away.  The  disadvantage  of 


PIERS  113 

the  solid-filled  piers,  especially  where  they  are  built  in 
groups,  is,  in  this  respect,  real  and  important. 

Filled-in  piers  may  have  greater  stability  than  pile  piers, 
depending  on  the  nature  of  the  retaining  structure,  but 
when  so  built  are  liable  to  do  more  damage  to  vessels  which 
may  collide  with  them. 

The  comparative  cost  of  pile  and  filled-in  piers  depends 
on  the  local  conditions  and  on  the  ratio  of  the  length  to 
width  of  the  prer,  the  filled-in  type  having  the  advantage 
where  the  width  is  very  great.  For  piers  in  Brooklyn  1300 
to  1800  feet  long,  the  filled-in  type  with  one-story  sheds 
was  considered  cheaper  for  widths  over  100  feet;  and  in 
Philadelphia,  for  a  length  of  550  feet,  the  economical  limit 
for  pile  piers  with  two-story  sheds  was  estimated  at  200 
feet. 

The  comparative  durability  of  a  filled-in  pier  depends  on 
the  nature  of  the  retaining  structure.  If  this  structure  is 
of  the  same  nature  as  that  of  the  sides  of  a  pile  pier,  there 
is,  when  decay  is  the  only  agent  of  destruction,  very  little 
advantage  in  favor  of  the  filled-in  type,  as  the  interior  portion 
of  a  carefully  designed  pile  pier  is  very  durable,  especially 
if  it  is  covered  with  a  shed.  Where  there  are  borers,  how- 
ever, a  solid-filled  pier  may  be  surrounded  by  a  cheap  non- 
permanent  type  of  marginal  construction  affording  a  smaller 
area  subject  to  the  action  of  the  borers  than  in  an  open 
pile  pier. 

One  of  the  most  important  objections  to  the  filled-in 
type  is  the  length  of  time  required  for  construction  and 
the  time  required  for  the  filling  to  settle  so  as  to  furnish  a 
stable  support  for  a  smooth  and  level  flooring  or  pavement, 
which  is  essential  for  the  economical  use  of  freight-handling 
trucks,  either  hand-operated  or  electrical.  The  solid-filled 
pier,  however,  will  ordinarily  support  a  comparatively  heavy 
live  load  on  those  portions  of  the  floor  not  near  the  edge. 

Filled-in  piers  are  less  combustible  than  wooden-pile 
piers  in  that,  even  when  surrounded  by  a  timber  platform, 
the  timber  'forms  only  a  small  portion  of  the  structure. 


114  WHARVES  AND  PIERS 

The  filled-in  type  has  a  great  advantage  whenever  a 
large  amount  of  excavated  material  has  to  be  disposed  of, 
in  that  it  affords  an  economical  method  of  utilizing  such 
material.  This  is  usually  the  case,  as  such  piers  are  generally 
located  where  the  water  is  shallower  than  that  required  for 
shipping  and  dredging  is  required  in  the  adjacent  slips  and 
channels.  Filled-in  piers  are,  however,  sometimes  built 
in  deep  water,  as  at  Victoria,  B.  C.,  where  the  depth  is  60 
feet. 

PILE-PLATFORM  PIERS 

Classification.  —  The  pile-platforrn  type  of  pier  may  be 
subdivided  into  various  classes,  according  to  the  nature 
and  material  of  the  piles  and  platform  as  follows: 

1.  Wood  piles  extending  up  to  deck. 

a.  Wood  caps  and  deck. 

b.  Wood  caps,  concrete  decks. 

c.  Concrete  caps  and  deck. 

2.  Wood  piles  cut  off  near  low  water. 

a.  Earth  or  cinder  fill  on  platform. 

b.  Reinforced  concrete  posts  or  cross  walls,  con- 

crete deck. 

3.  Composite  piles  of  wood  and  concrete. 

4.  Metal  piles  or  cylinders. 

a.  Cast-iron  piles. 

b.  Wrought-iron  or  steel  piles. 

c.  Wrought-iron  or  steel  cylinders. 

d.  Cast-iron  cylinders. 

5.  Reinforced  concrete  piles. 

6.  Reinforced  concrete  columns. 

There  are  other  possible  combinations  of  different  kinds 
of  piles  and  platforms,  some  of  which  are  described  in  this 
chapter. 

Advantages  of  Different  Classes.  —  Wooden  piles,  un- 
protected against  marine  borers,  are  not  suitable,  except 
for  temporary  structures,  in  waters  in  which  these  animals 
are  present.  If  a  pier  is  built  on  creosoted  piles  it  may  be 


PIERS  115 

expected  that  some  of  the  piles  will  need  renewal  at  the 
end  of  12  or  15  years,  and  as  the  worm-eaten  portion  cannot 
be  replaced  without  replacing  the  whole  pile,  they  must 
be  removed  and  replaced  or  additional  piles  driven  and 
pulled  under  the  caps.  This  requires  the  removal  of  a 
portion  of  the  deck  and,  if  there  is  a  shed  on  the  pier,  the 
removal  of  a  portion  of  the  roof.  On  the  other  hand,  where 
borers  are  absent,  the  various  types  in  class  1  are  suitable 
and  economical,  as  the  portions  of  the  piles  subject  to  decay 
can  be  replaced  by  splicing  on  new  pieces.  The  prices  for 
materials  and  other  local  conditions  in  New  York  have 
caused  this  class  of  construction  to  be  used  in  building  the 
municipal  piers  in  that  city.  The  building  of  wooden-decked 
piers  has  been  abandoned  as  far  as  possible  in  favor  of 
those  with  a  reinforced  concrete  deck,  as  the  wooden  deck 
is  the  part  of  the  structure  which  requires  the  largest  amount 
of  repairs  and  the  cost  of  the  concrete  deck  is  very  little 
more  than  that  of  wood.  This  type,  however,  is  not  used 
on  deep  mud  bottom  where  settlement  of  the  structure  is 
expected.  In  such  locations  a  thin  layer  of  reinforced 
concrete  is  placed  on  a  plank  deck  and  where  great  settle- 
ment is  anticipated  no  concrete  is  used  at  all.  This  type 
of  construction  is,  however,  subject  to  a  fire  risk  from 
floating  oil,  cotton  bales,  etc.,  which  may  drift  under  the 
pier. 

In  Philadelphia  conditions  as  to  borers,  tides,  shipping, 
etc.,  are  similar  to  that  in  New  York  and  in  designing 
municipal  piers  the  Department  of  Docks  and  Ferries 
obtained  bids  on  six  different  types  of  construction  in  order 
to  obtain  a  comparison  of  costs.  The  bids  showed  a  differ- 
ence of  only  8  cents  a  square  foot,  or  a  little  over  3  % 
between  the  design  similar  to  that  used  in  New  York  in 
which  the  piles  extend  up  to  a  reinforced  deck  and  one  in 
which  the  piles  were  cut  off  about  three  feet  above  mean 
low  water  and  supported  square  concrete  posts  or  columns 
carrying  reinforced  concrete  beams  and  deck  as  in  class  26 
in  the  table  above,  and  illustrated  in  Fig.  76. 


116  WHARVES  AND  PIERS 

In  considering  the  design  of  the  New  York  type  it  was 
estimated  that  the  tops  of  all  the  piles  would  have  to  be 
renewed  in  10  or  15  years.  This  is  very  different  from  the 
New  York  estimate  that  only  33|  %  would  have  to  be 
renewed  every  20  years.  As  the  difference  in  cost  would 
not  pay  for  splicing  the  number  of  piles  that  it  was  thought 
would  require  renewal  within  the  commercial  life  of  the 
pier,  and  as  the  latter  type  required  no  renewals  and  was 
free  from  the  fire  risk,  it  was  adopted.  Another  variation 
of  the  same  general  type  in  which  the  deck  is  supported  on 
concrete  walls  extending  from  side  to  side  of  the  pier  was 
also  used.  It  is  interesting  to  note  that  in  spite  of  the  above, 
recent  piers  in  New  York  City  are  being  built  on  a  plan 
similar  to  that  in  Fig.  70  with  the  exception  of  the  addi- 
tion of  side  caps.  The  contract  price  for  these  piers  is 
about  $1.20  per  square  foot,  including  the  asphalt  pavement, 
which  is  less  than  one  half  the  cost  of  the  Philadelphia 
piers.  It  must  be  remembered,  however,  in  making  the 
comparison,  that  the  New  York  piers  were  designed  for 
one-story  sheds  and  those  in  Philadelphia  for  two  stories 
with  very  heavy  live  loads  which  required  heavier  column 
foundations  and  more  piles. 

Concrete  pile  piers  have  a  disadvantage  in  comparison 
with  those  of  wood  in  that  it  is  difficult  to  brace  them 
transversely.  With  wood  piles  it  is  easy  to  apply  horizontal 
braces  just  above  mean  low  water  and  diagonal  braces 
between  them  and  the  caps,  thus  forming  a  truss  several 
feet  deep.  This,  so  far,  has  been  practically  impossible 
with  concrete  piles,  and  they  have  been  braced  entirely 
with  inclined  piles  or  by  deepening  the  caps  so  as  to  reduce 
the  length  of  that  portion  of  the  piles  subject  to  bending. 

A  difficulty  is  found  in  the  construction  of  piers  with 
concrete  superstructures,  in  the  support  of  the  forms  for 
the  girders,  joists  and  deck,  which  are  often  of  very  long 
span,  and  in  the  removal  and  transfer  of  the  forms  from 
bent  to  bent.  Steel  beams  encased  in  concrete  have  been 
used  in  many  cases  instead  of  reinforced  concrete  for  these 


PIERS 


117 


118 


WHARVES  AND  PIERS 


members,  as  they  support  themselves  as  well  as  the  forms 
for  the  deck. 

Piers  with  Wood  Piles  Extending  up  to  Deck.  —  While 
reinforced  concrete  may  be  more  economical  than  timber 
for  piers  where  the  estimated  life  of  the  structure  is  taken 
at  fifty  or  seventy-five  years,  it  usually  cannot  compare  in 
economy  with  timber  for  an  estimated  life  of  forty  years. 
For  this  reason  there  will  always  be  a  demand  for  good 
wooden  piers  whenever  lumber  of  good  quality  can  be 


Fig.  67.     Pier  with  Wooden  Piles  and  Deck.  B.  &  A.  R.  R.,  Boston,  Mass. 

obtained  at  low  prices,  as  on  the  Pacific  Coast  and  on  the 
Atlantic  since  the  opening  of  the  Panama  Canal. 

An  excellent  example  of  a  pier  of  the  class  designated  in 
the  table  as  No.  la,  of  a  type  adapted  to  general  use  is  that 
described  in  Chapter  III.  This  design,  after  over  forty 
years  of  experience,  has  undergone  little  alteration  and  is 
still  used  where  the  concrete  deck  is  not  desirable. 

The  North  German  Lloyd  Steamship  Company's  piers, 
which  were  built  to  replace  those  which  were  destroyed  in 
the  great  fire  in  1900  are  chiefly  notable  for  the  vertical 
sheathing  on  the  outside,  extending  from  the  deck  to  low 
water  and  for  the  layer  of  concrete  on  the  wooden  deck 
which  was  added  for  fire  protection.  This  concrete  carried 


PIERS 


119 


a  wearing  surface  of  plank.  A  section  of  these  piers  is 
shown  in  Fig.  66. 

Piers  of  this  class  on  the  Pacific  Coast  differ  notably 
from  the  above  in  the  use  of  2-inch  by  14-inch  joists  for 
supporting  the  deck  instead  of  12-inch  by  12-inch  "  rangers." 

In  1910  the  Boston  &  Albany  Railroad  constructed 
several  piers  at  East  Boston  to  replace  those  destroyed  by 
fire,  the  main  features  of  which  are  shown  in  Figs.  67  and  68. 


?  "Spruce  Wearing  Su'foc 


Section  at  Column 

Fig.  68.  Portion  of  Fig.  67  enlarged,  showing 
Column  Foundation,  Ventilator,  Floating  Fender 
and  Details  of  Deck. 

The  larger  piers  are  about  770  feet  long  and  250  feet  wide, 
and  the  slips  between  them  were  dredged  to  35  feet  at  low 
water.  A  part  of  the  central  portion  of  them  consists  of 
a  natural  bank  of  earth  extending  up  nearly  to  the  elevation 
of  high  water.  The  general  construction  is  of  timber  with 
wooden  piles.  Inclined  piles  were  used  freely  and  the  ten- 
foot  range  of  tide  with  the  deck  at  10J  feet  above  mean 
high  water  permitted  the  use  of  efficient  transverse  bracing 
on  the  vertical  piles.  In  one  of  the  piers  the  piles  are  cut 
off  2  feet  above  mean  low  water  and  capped,  the  deck  being 
supported  on  posts  resting  on  the  caps,  this  saving  in  the 


120  WHARVES  AND  PIERS 

length  of  the  piles  and  providing  an  easy  method  of  replacing 
a  portion  of  the  structure  subject  to  rot. 

These  piers  were  designed  with  the  purpose  of  providing 
cheap,  durable,  and  economical  structures.  Great  attention 
was  paid  to  fire  protection  and  the  prevention  of  rot.  A 
line  of  sheet  piling  was  driven  all  around  the  earth  cores  of 
the  piers  to  protect  the  sloping  banks  from  erosion.  From 
high  water  to  low  water  the  sides  of  the  piers  are  sheathed 
with  heavy  planking  to  exclude  burning  oil  and  other 
floating  materials.  This  sheathing  is  surmounted,  between 
high-water  mark  and  the  deck,  with  vertical,  reinforced 
concrete  slabs  4  inches  thick. 

Thorough  ventilation  is  provided  in  order  to  prevent  as 
far  as  possible  the  decay  of  the  timber.  This  is  accom- 
plished by  openings  2^  feet  by  3|  feet  spaced  9  feet  apart 
in  the  concrete  slabs  and  by  ventilators  on  the  sides  of  the 
track  pits.  A  novel  feature  is  the  provision  of  an  inspection 
walk  under  the  deck  to  facilitate  the  observation  of  the 
condition  of  the  structure,  particularly  in  regard  to  decay. 
The  decks  are  of  concrete  outside  the  sheds  and  inside  they 
are  of  unusual  construction,  being  formed  of  a  layer  of  4- 
inch  plank  on  which  are  placed  two  layers  of  four-ply 
plaster  board,  a  protecting  layer  of  J  inch  spruce,  and  a 
renewable  wearing  surface  of  2-inch  spruce. 

The  details,  fastenings,  and  bracing  of  these  piers  were 
designed  with  exceptional  care  and  thoroughness. 

In  designing  a  large  State  pier  for  New  London,  Connec- 
ticut, shown  in  Fig.  69,  a  combination  of  various  types  of  con- 
struction was  selected.  The  pier  consists  of  a  filled  portion 
100  feet  wide  surrounded  by  a  pile  platform  50  feet  wide. 
The  filled-in  portion  only  is  covered  by  a  shed.  The  pile 
platform  is  built  of  creosoted  piles,  caps,  and  bracing,  which 
support  a  deck  of  pre-cast  reinforced  concrete  slabs,  each  23 
feet  long  and  6  feet  wide,  weighing  about  7  tons.  The  slabs 
rest  on  the  pile  clamps,  but  are  not  fastened  to  them  in 
order  that  the  structure  may  not  be  so  rigid  as  to  injure 
vessels.  On  the  slabs  is  a  2-inch  asphalt  wearing  surface. 


PIERS 


121 


122  WHARVES  AND  PIERS 

The  shed  on  the  filled-in  portion  of  the  pier  is  to  be  used 
as  a  warehouse  and  not  merely  as  a  pier  shed  for  the  tempo- 
rary storage  of  cargo  in  transit  between  the  ship  and  ware- 
house. The  function  of  the  pile  platform  is  merely  that  of 
an  unshedded  pier  with  railroad  tracks  on  it.  The  absence 
of  the  necessity  for  covering  the  platform  with  a  shed  had 
a  decided  influence  on  the  design,  in  that,  as  the  shed  does 
not  cover  any  portion  of  the  platform  and  as  the  slabs  can 
be  removed  at  comparatively  small  expense,  any  portion 
of  the  piles  or  timber  structure  may  be  repaired  or  renewed 
without  destroying  the  deck  or  the  roof. 

The  retaining  walls  for  the  filling  are  of  riprap  surmounted 
by  rubble  walls  on  piles.  The  method  of  obtaining  a 
uniform  bearing  for  the  masonry  on  the  foundations  is 
interesting.  The  piles  were  driven  first,  and  the  riprap 
was  put  in  place  around  them.  Quarry  stones  were  then 
placed  on  top  of  the  riprap  in  such  a  way  as  to  form  a 
channel  on  top  of  each  row.  This  channel  was  lined  with 
waterproof  paper,  forming  a  mould  in  which  was  cast  a 
reinforced  concrete  girder,  which  conformed  to  the  tops 
of  the  piles,  no  matter  how  uneven  they  were  either  in  line 
or  elevation. 

The  design  adopted  for  this  pier  was  based  on  the  in- 
vestigation of  four  different  types:  these  were  (a)  steel 
cylinders  filled  with  concrete  supporting  steel  beams  encased 
in  concrete;  (6)  concrete  piles  and  deck;  (c)  wooden  piles, 
with  wood  deck  and  concrete  sheathing  and  (d)  creosoted 
piles  cut  off  at  mean  tide  and  supporting  inverted  concrete 
boxes  which  formed  the  deck.  The  economy  of  the  design 
was  calculated  on  the  assumption  that  the  commercial  life 
of  the  structure  would  be  only  twenty-five  years.  The 
total  cost  for  the  purposes  of  making  the  comparative 
estimates  was  considered  to  consist  only  of  the  original 
cost  and  the  serial  sum  of  the  interest  on  the  investment, 
and  the  annual  average  maintenance  charge. 

One  of  the  first  of  five  large  piers  built  with  wooden  piles, 
wooden  caps,  and  concrete  decks  is  that  at  33d  Street, 


PIERS 


123 


Brooklyn,  N.  Y.  It  is  shown  in  Fig.  70.  In  this  design 
the  wood  is  reduced  to  a  minimum,  even  the  side  caps 
which  in  the  previous  designs  of  the  New  York  Dock  De- 
partment were  placed  on  the  side  piles  below  the  cross  caps 
or  clamps  were  omitted.  The  cross  rows  of  piles,  spaced 
10  feet  apart,  were  braced  and  clamped  in  the  usual  manner, 
except  for  the  omission  of  the  side  caps  and  the  addition 
of  four  rows  of  longitudinal  bracing  which  were  found 

^"Distributing  Rods 
/'      .^Diam.Tension  RocfsYl°'^%     '£ 

— ^- 


Half   Cross-  Section    at   Foundation   Row 


Half  Cross   Section    at  Intermediate    Row 

Fig.  70.     Pier  with  Wooden  Piles  and  Reinforced  Concrete  Deck.,  33rd  St., 

Brooklyn,  N.  Y. 

necessary  to  hold  the  transverse  rows  of  piles  straight  during 
the  construction  of  the  decks. 

The  illustration  shows  the  method  of  constructing  the 
concrete  deck.  The  slabs  were  cast  in  alternate  bays  10 
feet  wide  extending  from  side  to  side  of  the  pier.  It  was 
intended  to  have  the  granolithic  finish  on  the  concrete  act 
as  the  wearing  surface,  but  it  did  not  prove  durable  and  the 
deck  was  covered  with  a  IJ-inch  asphalt  pavement. 

Provision  was  *  made  for  carrying  sewer  boxes  to  the 
outer  end  of  the  pier,  as  shown  in  the  illustrations. 


124 


WHARVES  AND  PIERS 


The  pier  carries  a  single-story 
steel  shed  with  four  rows  of 
posts.  The  two  outer  rows  of 
piles  are  spaced  twelve  feet 
apart  and  the  deck  over  this 
portion  consists  of  a  concrete 
slab  reinforced  with  wire  mesh, 
supported  on  wooden  planks 
resting  on  rangers  built  up  of 
two  12-inch  by  12-inch  timbers 
placed  one  on  top  of  the  other. 

Adjacent  piers  commenced 
within  the  last  year  have  the 
wooden  side  caps  restored,  as  it 
was  found  that  their  omission 
allowed  lighters  to  float  under 
the  deck  of  the  pier  and  rip  it 
up  when  the  tide  rose  or  when 
there  was  a  heavy  swell. 

A  freight  pier  of  this  type 
for  the  Central  Railroad  of 
New  Jersey  at  Communipaw  is 
notable  in  that  all  the  piles  and 
lumber  are  creosoted  to  prevent 
decay  and  that  the  presence  of 
rock  under  the  sand  and  gravel 
of  the  bottom  allowed  a  pene- 
tration of  only  8  feet  for  the 
piles.  To  give  the  structure 
stability  cribs  extending  from 
side  to  side  of  the  pier  and 
covering  the  space  of  four  rows 
of  piles  were  placed  at  the  outer 
end  and  midway  between  that 
point  and  the  bulkhead. 

In  Boston  concrete  caps  and 
deck  on  wooden  piles  were 


PIERS 


125 


used  in  the  reconstruction  of  Commonwealth  Pier  No.  5, 
shown  in  Figs.  71  and  72.  This  pier  was  built  in  1900  and  re- 
built in  1913,  the  wooden  pile-caps  and  decks  being  replaced 
with  concrete  beams  and  slabs.  Where  a  portion  of  the 


Section   G'H 


^"Spacing Kbds-.  sfKhMbk        T6  /Jw?/.,g- 


Section     E-F 


r  Spacing 


"Cross- Section    of    Platform.  Burned  Section 


Fig.  72.  Pile  Platform  with  Wooden  Piles  and  Reinforced  Concrete  Caps 
and  Decks.      Commonwealth  Pier  No.  5,  Boston,  Mass. 

platform  had  been  destroyed  by  fire  the  concrete  beams 
were  7|  feet  deep  and  extended  down  practically  to  high 
water.  A  feature  was  the  placing  of  cast-iron  extension 
piles  in  the  beams,  so  that  the  latter  would  be  supported  in 
case  the  lower  portion  should  be  disintegrated  by  frost  and 
sea  water. 


126 


WHARVES  AND  PIERS 


Piers  with  Wooden  Piles  Cut  off  near  Low  Water.  —  The 
pier  on  wooden  piles  with  the  platform  at  low-water  level 
with  incombustible  materials  above  has  the  advantage  over 
the  type  in  which  the  piles  extend  up  to  the  deck,  that  no 
portion  of  the  structure  is  subject  to  decay  and  that  it  is 
free  from  fire  risk  from  cargo  on  deck,  vessels  alongside,  or 
from  burning  oil,  cotton  bales,  or  similar  articles  floating 
under  it. 

When  the  platform  supports  a  solid  filling  held  in  place 
by  a  masonry  wall  it  has  the  disadvantage  that  the  piles 


Fig.  73.     Pier  with  Platform  at  Low  Water  Level  on  Wooden  Piles, 
D.  L.  &  W.  R.  R.,  Hoboken,  N.  J. 

carry  a  heavy  dead  load  and  many  more  piles  are  required 
than  in  class  1  or  in  class  2,  where  the  platform  supports  a 
concrete  deck  on  posts. 

This  type  is  not  suitable  for  waters  in  which  the  marine 
borers  are  active,  even  if  the  piles  are  creosoted,  if  a  life  of 
more  than  fifteen  or  twenty  years  is  desired,  as  the  nature 
of  the  structure  above  the  platform  renders  the  renewal  of 
the  piles  practically  impossible  when  the  creosote  is  washed 
out  and  the  piles  are  eaten  away. 

A  pier  of  class  2a,  100  feet  wide  and  600  feet  long,  is 
shown  in  Fig.  73.  In  this  case  the  pier  was  built  by  a 
railroad  which  had  close  at  hand  a  large  supply  of  cinders, 


PIERS 


127 


which  afforded  a  cheap  and  light  material  for  filling.  The 
mud  at  this  location  was  185  feet  deep  and  the  piles  were 
85  feet  to  95  feet  long.  They  were  driven  3  feet  apart  in 
transverse  rows  5  feet  apart  and  were  designed  for  maximum, 
loads  of  12  tons.  The  depth  of  water  at  the  sides  of  the 
pier  varied  from  20  to  30  feet. 

Another  pier  near  by  has  a  portion  of  the  piles  in  hard 
bottom  and  a  portion  entirely  in  mud.  In  this  case  the 
loading  is  varied  from  17  to  12  tons,  according  to  the  nature 
of  the  bottom. 

An  example  of  type  2b  is  that  adopted  for  some  piers  at 
the  U.  S.  Navy  Yard  in  Brooklyn,  Fig.  74.  In  this  case 


Pit 


Vpes     l*T"/f  J 1  Wood  Block 

P     •-.,.  Cable&Elec.  )f?.R.Track: Pavement? 


t< ' 

/P  /f!  Tracks  Due  h  •. 


Columns  ore 
precast  in  units 
and  keyed  fa      6 
the  cross  octps. 


2-0'- 


Fig.  74.     Pier  with  Timber  Piles  supporting  Reinforced  Concrete  Deck 
on  Reinforced  Concrete  Posts,  Navy  Yard,  Brooklyn,  N.  Y. 

reinforced  concrete  columns  with  spreading  tops  were  cast 
on  shore  and  fastened  to  a  timber  platform  on  piles,  located 
just  above  low  water,  by  keys  and  wedges.  A  reinforced 
concrete  deck  was  then  laid  on  top  of  the  columns.  This 
method  avoided  all  the  uncertainties  of  concrete  deposited 
in  forms  below  high- water  mark  and  subject  to  the  action 
of  the  water  before  hardening,  did  not  put  a  very  heavy 
unit  load  on  the  supporting  piles,  and  gained  all  the  ad- 
vantages of  the  low,  platform  type.  Some  criticism  has 
been  made,  however,  of  the  possible  plane  of  weakness 
between  the  platform  and  the  concrete  structure  which  it 
supports. 
In  Philadelphia  two  piers,  each  550  feet  long  and  180 


128 


WHARVES  AND  PIERS 


feet  wide,  with  wooden  piles  cut  off  just  above  low  water 

^  ^    and  with  concrete  above  have  re- 

^!i  ^    cently   been   built.     One  has  cross 

if\*i>  **J|  o3 

walls    of     concrete     supported    on 


a: 


^    double  rows  of  piles  20  feet  apart 

o3  -  , 


:=     3  and  one  has  columns  on  groups  of 

^  piles  spaced  20  feet  in  each  direction. 

g  The  tidal  range  is  about  6  feet  and 

g  the  concrete  walls  and  columns  were 

1  cast  between  tides.     The  two  sec- 

^  tions  are  shown  in  Fig.  75.     These 

°  designs  were    selected  from  six  on 

1  which    bids    were    received.      The 

A  . 

T5  other  designs  were  for  pile  platform 

*  types  2a  and  Ib  and  solid-filled 
piers.  The  second  of  the  chosen 
designs  was  the  cheaper,  but  it  was 

2  desired   to  give  both  a  trial,  as  a 


—    (!)       O 


O     'S 


=== — —  ^    number  of  similar  piers  was  to  be 
built. 

Piers  on  Composite  Piles  of 
Wood  and  Concrete.  —  Two  large 
steamship  piers  have  been  built  in 
the  tropics  on  wooden  piles  pro- 
g  tected  with  concrete,  one  at  Bocas 
del  Toro,  Panama,  and  one  at  Port 
au  Prince,  Haiti. 

The  pier  at  Bocas  del  Toro  is 
o  shown  in  Fig.  77. 1  It  was  built 
^  parallel  to  the  shore  on  a  shelving 
g§  bottom,  where  the  water  was  10  feet 
|  deep  on  one  edge  of  the  structure 
£  and  22  feet  on  the  outshore  side, 
o  The  tidal  range  was  only  9  inches 
be  and  the  locality  was  free  from 
k  ocean  swells.  Untreated  wo'oden 

1  T.  H.  Barnes  "  The  Reinforced  Concrete  Wharf  of  the  United  Fruit  Com- 
pany at  Bocas  del  Toro,  Panama."     Trans.  Am.  Soc.  C.  E.,  Vol.  LXXI,  p.  295. 


r- F 


PIERS 


129 


piles  were  driven  ten  feet  apart  in  both  directions,  with 
an  average  penetration  of  40  feet,  and  over  them 
were  placed,  by  a  floating  pile-driver,  tapering,  conical, 
reinforced  concrete  shells,  extending  from  below  the  mud 


130 


WHARVES  AND  PIERS 


line  to  above  high  water.  These  shells  are  2  inches  thick, 
20  inches  in  diameter  inside  at  the  top,  and  16  inches  at 
the  bottom.  The  space  between  the  pile  and  the  shell  was 
sealed  with  concrete  deposited  through  the  water,  the 
water  pumped  out,  and  the  remaining  space  filled  with  lean 
concrete  to  within  5  feet  of  the  top  of  the  shell.  Reinforce- 
ment for  the  columns  which  extended  from  the  tops  of  the 
shells  to  the  pile  caps  was  then  put  in  place,  the  shells 


Fig.   77.     Pier  with  Composite   Piles  and    Reinforced 
Concrete  Deck,   Bocas  Del  Roro,  Panama. 

filled  to  the  tops,  and  the  whole  protected  pile  straightened 
and  stay-lathed.  Forms  supported  by  steel  rails  which 
rested  on  the  tops  of  the  shells  were  then  built  for  the 
reinforced  concrete  columns,  beams,  braces  and  slabs,  and 
the  concrete  portion  of  the  structure  completed. 

One  of  the  most  difficult  points  in  the  design  of  nearly 
all  concrete  piers  is  the  transverse  bracing,  and  a  notable 
feature  of  this  pier  is  the  use  of  horizontal  and  diagonal 
braces  of  reinforced  concrete.  These  were  successfully 
constructed,  though  with  some  difficulty.  The  horizontal 


PIERS 


131 


braces  were  placed  at  about  mean  high  water  and  the 
diagonals  had  a  rise  of  about  4J  feet,  the  deck  being  about 
8J  feet  above  mean  tide. 

The  shells  were  reinforced  with  electrically  welded  wire 
fabric  with  a  6-inch  square  mesh.  They  were  from  16  to 
30  feet  long  and  were  made  at  the  rate  of  about  six  in  a 
day. 

It  was  estimated  that  the  pier  cost  about  as  much  as  one 
built  of  creosoted  piles  with  creosoted  timber  beams  and 
deck,  but  that  it  would  last  much  longer,  as  the  life  of  such 
piles  was  considered  to  be  only  15  years.  Various  designs 
for  concrete  piles  were  considered,  but  were  discarded,  as 


Port  Section  A-A 


Port  Section  B-B 


Fig.  78.     Pier  with  Composite  Piles  and  Reinforced  Concrete  Deck,  Port 
au  Prince,  Haiti. 

the  length  of  70  feet,  which  was  required,  was  unprecedented 
in  1906,  when  this  pier  was  built. 

Only  a  small  plant  was  required  consisting  of  a  floating 
pile-driver  in  addition  to  the  stone  crusher  and  concrete 
mixer. 

The  slab  is  7  inches  thick  and  calculated  for  250  pounds 
live  load. 

Test  piles  were  driven  and  loaded  to  determine  the 
bearing  power. 

A  pier  of  similar  construction  was  completed  at  San 
Francisco  in  1913.  It  was  800  feet  long  and  126  feet  wide. 
The  pile  caps  were  of  steel  encased  in  concrete  and  carried 
wooden  stringers  and  a  plank  deck. 

A  pier  at  Port  au  Prince,  Haiti,  was  built  in  1912  on 
timber  piles  protected  by  encasing  them,  before  driving, 


132  WHARVES  AND  PIERS 

with  wire  mesh  and  cement  mortar.  The  pier  is  825  feet 
long  and  from  50  to  60  feet  wide,  and  is  located  in  water 
with  a  minimum  depth  of  27  feet.  The  design  is  shown  in 
Fig.  78  and  the  method  of  constructing  the  pile  in  Fig. 
79.  The  piles  had  a  maximum  length  of  57  feet  and  the 
penetration  varied  from  15  to  30  feet.  The  protective 
coating  on  the  piles  reached  from  the  tops  to  within  5  feet 
of  the  points.  They  were  spaced  10  feet  apart  each  way, 
and  were  capped  with  reinforced  concrete  girders  18  inches 
wide  and  5  feet  6  inches  deep,  arched  between  the  piles, 
supporting  longitudinal  beams  and  a  5  to  7  inch  slab.  The 


Fig.  79.    Composite  Pile,  Port  au  Prince,  Haiti. 

forms  for  the  superstructure  were  supported  by  means  of 
wooden  collars  clamped  to  the  piles. 

Piles  of  somewhat  similar  construction,  in  which  the 
mortar  was  applied  by  the  cement  gun,  were  used  in  con- 
structing a  bulkhead  wall  at  San  Juan,  Porto  Rico,  in  1913. 
These  piles  were  driven  to  a  20-ton  bearing  with  a  3000- 
pound  drop  hammer  without  damage  to  the  protective 
coating. 

Piers  on  Metal  Piles  or  Cylinders.  —  Before  the  advent 
of  reinforced  concrete,  piers  on  piles  or  large  cylinders  of 
cast  iron,  wrought  iron,  or  steel  were  built  in  many  places 
where  marine  borers  were  active.  Some  have  withstood 
corrosion  very  well  and  have  lasted  for  30  years  or  more 
and  some,  notably  those  built  on  piles  made  of  steel  pipes, 


PIERS  133 

for  steamboat  landings  on  the  ocean  shore,  have  lasted 
only  10  years  before  they  needed  extensive  repairs. 

One  of  the  earlier  piers  of  this  design  was  built  at  Fortress 
Monroe,  Va.,  thirty-two  years  ago.  This  pier  was  designed 
for  a  steamboat  landing  and  is  in  a  location  exposed  to 
strong  winds  and  currents  and  at  times  a  heavy  sea.  The 
piles  were  of  cast  iron,  one  inch  thick,  and  where  there  was 
a  firm  bottom,  had  a  disc  on  the  lower  end  and  were  jetted 
into  place.  In  a  portion  of  the  pier  where  there  was  a  layer 
of  mud  overlaid  with  sand,  creosoted  wooden  piles  were 
first  driven  and  cut  off  above  the  bottom;  cast-iron  screw 
piles  were  then  forced  down  over  them.  All  the  iron  piles 
were  pumped  out  and  filled  with  concrete.  A  platform  of 
creosoted  piles  with  wooden  deck  was  built  around  the  por- 
tion of  the  pier  at  which  the  steamboats  landed,  as  the  iron 
structure  was  thought  to  be  too  lacking  in  elasticity  for 
boats  to  lie  alongside  it.  Recent  reports  state  that  the  cast- 
iron  piles  are  in  as  good  condition  as  when  put  in  place,  but 
that  the  beams  of  the  deck  are  badly  corroded,  the  scale 
being  J  inch  or  more  in  thickness. 

An  iron  coal  pier  was  built  at  Lamberts  Point,  Norfolk, 
Va.,  in  1892  which  carried  an  elevated  steel  railroad  struc- 
ture for  loading  coal.  The  piles  were  of  commercial  tubing 
12  inches  in  diameter  and  J  inch  thick,  45  to  57  feet  long, 
and  were  filled  with  concrete.  They  were  fitted  with  discs 
4  feet  in  diameter  and  were  jetted  into  place  in  a  sand 
bottom.  The  jetting  was  aided  by  pulling  down  on  the 
piles  and  each  pile  was  weighted  to  bring  it  to  a  firm  bearing. 
The  iron  piles  were  surrounded  by  a  braced  fendering  of 
creosoted  piles.  Iron  cross  bracing,  extending  considerably 
below  the  low-water  line,  was  used  to  give  lateral  strength. 

An  ocean  pier  for  a  steamboat  landing  was  built  in  1879 
at  Coney  Island,  N.  Y.,  of  wrought  iron  tubular  piles  about 
57  feet  long  and  8f  inches  in  the  outside  diameter  and  \ 
inch  thick.  They  were  fitted  with  cast-iron  discs  and  were 
sunk  from  12  to  15  feet  into  a  sand  bottom.  This  pier  had 
two  decks  12  and  24  feet  above  high  water  and  the  piles 


134  WHARVES  AND  PIERS 

were  cross  braced  between  the  water  and  the  lower  deck. 
Another  pier  of  somewhat  similar  construction  was  built 
at  the  same  place  several  years  later. 

Another  example  of  a  tubular  steel  pile  pier  is  that  built 
in  the  open  ocean  for  a  steamboat  landing  at  Atlantic  City, 
N.  J.,  in  1897-1898.  The  piles  were  10f  inches  in  outside 
diameter  and  f  of  an  inch  thick  and  the  caps  were  of  plate- 
girder  construction.  In  1905  the  piles  and  particularly 
the  girders  had  rusted  so  that  they  were  reduced  in  section 
by  from  •§•  to  ^.  The  pier  was  entirely  rebuilt  by  encasing 
the  piles  and  beams  in  reinforced  concrete  designed  to 
take  the  entire  load  independent  of  the  remaining  strength 
of  the  original  structure. 

Another  similar  pier  was  built  at  Old  Orchard  Beach,  Me. 

Many  piers  have  been  built  with  iron  or  steel  cylindrical 
columns  filled  with  concrete,  both  plain  and  reinforced. 

A  wharf  of  this  type  was  built  at  Tampico,  Mexico,  in 
1900,  for  the  shipment  of  petroleum,  to  replace  one  of 
creosoted  timber  which  had  been  burned  to  the  water  line. 
The  bottom  at  the  site  of  the  wharf  was  formed  of  fine 
sand  about  50  feet  below  the  water  level  overlaid  with 
silt.  The  cylinders  were  about  50  feet  long  and  6  feet  in 
diameter  of  ^-inch  steel  plate,  except  the  portions  above 
water,  which  were  f  inches  thick.  Most  of  the  cylinders 
were  sunk  by  pulling  down  with  jacks  attached  to  the  old 
piles  and  by  driving  with  a  light  hammer,  but  some  were 
sunk  by  the  pneumatic  process.  Piles  were  driven  inside 
the  cylinders  by  means  of  a  30-foot  follower,  and  extended 
into  the  sand.  The  mud  and  water  were  removed  from 
the  cylinder  and  they  were  filled  with  concrete,  the  portion 
required  for  sealing  being  placed  by  means  of  a  tremie. 
They  were  spaced  about  20  feet  apart  each  way  and  were 
calculated  to  carry  from  116  to  235  tons  each.  The  deck 
was  of  steel  beams  supporting  a  concrete  arched  flooring 
designed  for  a  live  load  of  800  pounds  per  square  foot. 
The  two  upper  sections  of  some  of  the  cylinders  were  gal- 
vanized and  the  piles  were  creosoted.  The  purpose  of 


PIERS 


135 


creosoting  the  piles,  which  were  entirely  protected  by  the 
concrete,  silt,  and  water  from  rot  and  borers  is  not  apparent. 
The  design  is  well  shown  in  Fig.  80. 


Fig.  80.     Wharf  with  Steel  Cylinders,  Tampico,  Mexico. 

Two  piers  of  similar  construction,  one  of  which  was  70 
feet  wide  and  600  feet  long,  were  built  in  Manila  in  1906. 
The  columns  were  spaced  20  by  25  feet.  They  rest  on 
clusters  of  piles  cut  off  at  various  heights.  The  steel  shells 
were  placed  over  the  piles,  the  mud  and  water  pumped  out, 


136  WHARVES  AND  PIERS 

the  bottom  sealed  with  concrete,  reinforcement  placed,  and 
the  shells  filled  with  concrete.  The  columns  were  capped 
with  plate  girders  carrying  steel  beams  and  a  reinforced  con- 
crete slab  with  a  wood  block  pavement  at  10  feet  5  inches 
above  mean  low  water.  The  steel  cylinders  were  very  thin 
in  these  piers  and  the  concrete  which  filled  them  was  heavily 
reinforced.  Such  cylinders  act  merely  as  forms  for  the 
concrete  above  the  bottom,  as  they  soon  rust  away.  The 
cylinders  were  braced  with  diagonal  rods  of  steel. 

Another  huge  coal  pier  was  recently  completed  at  Lam- 
berts Point,  Norfolk,  Va.,  in  which  the  steel  superstructure 
which  carried  the  railroad  tracks  was  supported  on  steel 
cylinders  41  feet  high  and  18  feet  in  diameter  filled  with 
concrete  resting  on  piles  which  were  driven  by  means  of  a 
follower  and  telescopic  leads  to  27  feet  below  low  water. 
The  concrete  was  not  reinforced.  A  protective  structure 
of  timber  with  creosoted  piling  was  built  around  the  cylinders 
to  provide  wharfage  for  vessels. 

A  pier  with  cast-iron  cylinders  30  inches  in  diameter  and 
If  inches  thick  was  built  at  Cienfuegos,  Cuba,  in  1906. 
The  cylinders  weighed  420  pounds  per  linear  foot  and 
carried  a  load  of  50  tons  each.  They  were  braced  with 
2-inch  square  steel  rods.  The  deck  beams  were  steel-plate 
girders  and  the  deck  was  of  reinforced  concrete. 

One  of  the  first  ventures  in  the  use  of  reinforced  concrete 
piles  for  large  steamship  piers  is  found  in  those  built  by  the 
Atlantic  and  Birmingham  Railway  at  Brunswick,  Ga., 
which  were  completed  in  1907.  Two  piers  were  built  140 
feet  wide,  one  350  and  one  750  feet  long,  and  the  method 
of  construction  is  shown  in  Fig.  81.  The  superstructure 
was  entirely  of  wood.  The  piles  are  rectangular,  10  inches 
by  16  inches  in  section  and  from  32  to  50  feet  long,  and  were 
driven  by  jetting  through  a  centrally  located  pipe.  The 
deck  of  the  pier  is  7  feet  above  high  water  and  14  feet  above 
low  water.  The  piles  were  capped  with  double  timbers 
resting  one  on  each  side  on  shoulders  in  the  piles.  The 
caps  carry  6-inch  by  14-inch  wooden  joists  notched  down  on 


PIERS 


them  and  fastened  with 
drift  bolts,  and  a  3-inch 
plank  deck  was  laid  on 
the  joists.  Horizontal 
braces  of  creosoted  6-inch 
by  10-inch  lumber  were 
bolted  to  the  piles  just 
above  low  water  and 
four  rows  of  inclined 
braces  were  placed  be- 
tween the  horizontal 
braces  and  the  caps.  In 
order  to  make  the  sides 
of  the  piers  elastic,  so  as 
not  to  injure  vessels  lying 
alongside,  the  outside 
row  of  bearing  piles  on 
each  side  was  of  creosoted 
timber  braced  with  in- 
clined piles  and  protected 
by  fender  piles  of  the 
same  material.  The  pier 
sheds  did  not  project  be- 
yond the  concrete  piles, 
so  that  the  wooden  piles 
could  be  renewed  with- 
out making  holes  in  the 
roof  of  the  shed.  One  of 
these  piers  was  rammed 
by  a  steamer  during  the 
construction,  without 
serious  damage  to  the 
structure. 

A  similar  pier  was  built 
at  the  U.  S.  Navy  Yard 
at  Charleston,  S.  C. 

In  reconstructing  the 
steel  pier  on  the  ocean 


138  WHARVES  AND  PIERS 

shore  at  Atlantic  City  in  1906  additions  were  made  with  re- 
inforced concrete  piles.  A  portion  of  them  were  of  12  inches 
diameter  with  a  maximum  length  of  32  feet  6  inches,  driven 
8  to  14  feet  into  the  sand,  and  part  were  25  inches  in  diam- 
eter with  a  maximum  length  of  52  feet  and  a  penetration  of 
16  feet.  The  12-inch  piles  were  cast  on  end  complete  with 
knee  braces  at  the  upper  end.  The  25-inch  piles  had  the 
lower  12-feet  first  cast  in  one  piece.  A  watertight  form  of 
galvanized  steel  or  of  wood,  long  enough  to  reach  above  the 
water  when  the  pile  was  in  place,  was  then  attached  to  the 
12-foot  section,  which  with  the  concrete  form  was  then 
jetted  down  to  the  required  depth  and  the  form  filled  with 
concrete.  Both  the  steel  and  wooden  forms  were  left  on 
the  piles.  The  piles  had  enlarged  bulbs  on  the  lower  ends, 
30  inches  and  42  inches  in  diameter  respectively,  to  give 
additional  bearing  power. 

The  original  steel  piles  were  encased  in  a  reinforced  con- 
crete jacket  with  a  wooden  outer  form  and  a  sheet-steel  inner 
form.  These  jackets  were  cast  above  water  in  section  of  con- 
venient length,  as  they  were  sunk  by  water  jets  to  the  discs 
at  the  lower  end  of  the  steel  piles.  The  space  between  the 
concrete  jacket  and  the  steel  pile  was  filled  with  concrete. 
The  details  of  the  25-inch  new  piles  are  shown  in  Fig.  82. 

A  pier  in  which  piles  of  somewhat  similar  construction 
were  used  was  built  to  serve  as  a  recreation  pier  and  to  carry 
a  sewer  outfall  pipe  at  Santa  Monica,  Cal.,  in  1908.  It 
was  1600  feet  long  and  35  feet  8  inches  wide,  24  feet  above 
mean  low  water,  and  the  depth  of  water  at  the  outer  end 
was  25  feet.  There  were  three  piles  in  a  bent  and  the  bents 
were  20  feet  apart.  The  piles  were  14,  18,  and  23  inches 
in  diameter  and  had  a  30-inch  bulb  at  the  lower  end.  They 
were  about  70  feet  long  at  the  outer  end  of  the  pier.  They 
were  driven  by  the  water  jet,  a  pipe  being  cast  for  the 
purpose  in  the  axis  of  each  pile.  The  14-inch  piles  on  a 
portion  of  this  pier  were  jacketed  with  a  steel  cylinder  22 
inches  in  diameter,  made  of  No.  10  plate  from  2  feet  above 
high  water  to  2  feet  6  inches  below  the  ground  line, 


PIERS 


139 


the  space  between  the  jacket  and  the  pile  being  filled  with 
concrete.  The  piles  in  the  outer  portion  of  the  pier  were 
not  jacketed,  as  it  was  found  that  they  were  covered  with  a 
heavy  protecting  growth  of  mollusks  soon  after  they  were 
driven.  There  were  three  rows  of  beams  of  9-inch  by  18- 
inch  reinforced  con- 
crete between  the 
bents  to  give  longi- 
tudinal stiffness. 
The  pile  caps  of  9- 
inch  by  30-inch  rein- 
forced concrete  car- 
ried 4-inch  by  16-inch 
by  22-feet  fir  joists 
spaced  30  inches 
apart  and  stiffened 
by  2  rows  of  2  by  4 
bridging  in  each  bent. 
On  the  joists  were 
laid  2-inch  plank  and 
a  3-inch  concrete 
slab. 

Another  ocean  pier 
was  built  on  rein- 
forced concret  piles 
at  Long  Branch,  Fig' 82' 
N.  J.,  in  1912.  The 
piles  were  hollow,  22  inches  square  outside,  with  a  circular 
hole  in  them  13  inches  in  diameter.  They  were  from  45  to 
68  feet  long  and  were  driven  into  the  sand,  clay,  and  gravel 
bottom  about  22  feet  by  means  of  four  water  jets.  A  150 
H.  P.  pump  was  required.  The  deck  of  the  pier  was  22  feet 
above  low  water  and  the  outer  portion  of  the  pier,  which 
was  intended  for  a  landing  place  for  steamboats,  was  braced 
with  inclined  piles.  The  shell  of  the  hollow  piles  was  of  1 : 
1J:3  concrete  and  the  interior  portion  was  filled  with  a 
leaner  mixture.  The  hollow  section  of  the  piles  provided 


Ocean  Pier  with  Reinforced  Concrete 
Piles,  Atlantic  City,  N.  J. 


140 


WHARVES  AND  PIERS 


a  convenient  means  of  splicing  those  which  were  too  short 
to  reach  the  hard  gravel  layer  to  which  it  was  desired  to 
drive  them  or  which  could  not  be  economically  handled  if 
made  of  the  required  length  in  one  piece,  rods  being  placed 
in  the  core  to  strengthen  the  joint.  Piles  made  with  this 


/^       J^^^^J— ^-  ---U 

Longitudinal  Section  of  t2$30' Girders 


Elevation  of  Fenders 


Cross  Section 
Through  Wales 

Fig.  83.     Reinforced  Concrete  Pile  Pier, 
Oakland,  Cal. 


rich  mixture  have  proved  durable  in  this  locality,  while 
those  of  1:  2:  4  concrete  have  been  badly  abraded  by  the 
sand  on  the  beach  between  high  and  low  water.  The 
caps,  joists,  and  deck  of  this  pier  were  of  reinforced  concrete. 
Another  pier,  one  of  the  first  large  piers  entirely  of  con- 
crete, 295  feet  long  by  124  feet  wide,  was  built  at  Oakland, 
Cal.,  in  1911  and  is  illustrated  in  Fig.  83.  The  piles 
were  octagonal,  16  inches  in  their  short  diameter  and  from 
30  to  50  feet  long.  Driving  the  piles  with  a  hammer  in 


PIERS  141 

the  clay  and  tightly  packed  gravel  of  the  bottom  fractured 
the  heads  and  they  were  put  in  place  by  jetting  and  "  churn- 
ing" or  "  spudding."  Horizontal  bracing  was  provided  by 
putting  in  three  concrete  brace  walls  reaching  from  the 
deck  to  the  water,  extending  about  21  feet  each  side  of  the 
centre  line  of  the  pier.  The  deck  system  is  of  reinforced 
concrete  girders  and  beams  supporting  a  4-inch  reinforced 
concrete  slab  with  a  2-inch  asphalt  pavement.  Fenders 
are  of  the  timber  and  car-spring  type  and  the  mooring  piles 
are  of  timber  driven  through  holes  in  the  deck.  All  timber 
was  creosoted.  Concrete  of  1:  1|:  3  mixture  was  used  for 
the  upper  five  feet  of  the  piles  and  1:  2:  4  for  the  bal- 
ance. 

The  piles  were  spaced  about  10  feet  in  each  direction. 

Three  notable  steamship  piers  have  recently  been  built 
on  reinforced  concrete  piles  of  great  length,  one  at  Halifax, 
N.  S.,  where  the  climatic  conditions  are  most  severe,  and 
two  at  Havana,  where  the  conditions  in  a  tropical  climate 
and  a  sheltered  harbor  are  most  favorable  for  the  durability 
of  the  concrete.  In  the  Halifax  pier  the  piles  were  placed 
in  rows  and  carried  the  deck  on  the  ordinary  girder  and 
beam  construction,  but  at  Havana  they  were  driven  in 
clusters  and  the  deck  slab  was  carried  on  shallow  beams 
between  rectangular  pile  caps.  At  Halifax  inclined  piles 
were  used  throughout  the  pier  to  give  lateral  stiffness,  but 
at  Havana  bracing  piles  were  used  only  in  the  two  outer 
rows  of  pile  clusters,  as  it  was  not  considered  that  they  would 
give  sufficient  stiffness  in  addition  to  that  afforded  by  the 
piles,  the  weight  of  the  structure  with  its  two-story  con- 
crete shed,  and  the  connections  between  the  piles  and 
caps,  to  pay  for  their  extra  cost.  For  the  construction  of 
the  Halifax  piers  an  enormous  combined  floating  pile-driver 
and  derrick  was  built,  but  at  Havana  the  piles  were  placed 
with  a  floating  derrick  and  driven  by  a  steam  hammer 
resting  on  and  fastened  to  the  heads  of  the  piles.  Piles 
were  chosen  for  the  Havana  design  instead  of  the  large 
columns  such  as  are  used  on  the  Pacific  Coast  because  they 


142 


WHARVES  AND  PIERS 


were  considered  the  cheaper  on  account  of  the  length  of 
the  columns  required. 

A  notable  difference  between  the  two  designs  was  that 
while  both  piers  had  to  carry  two-story  sheds,  the  Halifax 
pier  was  calculated  to  carry,  a  live  load  of  1000  pounds  on 
the  first  floor  and  500  on  the  second  and  110  on  the  roof, 
and  those  at  Havana,  only  250  and  400  pounds  respectively, 


r         juZ        ru 

M          "  '"  ; -&'°— H 

M^r'zfca>tm/7       ^,^  !  ,j&*          j>6'- 


Fig.  84.     Reinforced  Concrete  Pile  Pier,  Halifax,  N.  S. 

and  none  on  the  roof.  At  both  places  large  yards  and 
considerable  plant  were  necessary  for  fabricating  the  piles, 
handling  them  in  the  yard,  and  transferring  them  to  the 
piers. 

The  Halifax  pier  is  shown  in  Fig.  84.  This  pier  is  one 
of  four  to  be  built  in  the  inner  harbor.  It  is  693  feet  long 
and  235  feet  wide,  located  in  water  60 .  to  70  feet  deep,  on 
a  rock  bottom,  61  to  87  feet  below  the  pier  floor,  overlaid 
by  from  5  to  12  feet  of  clay  and  hard  pan  and  with  30  feet 
of  soft  mud  at  the  shore,  and  5  feet  at  the  outer  end.  The 


PIERS 


143 


mean  range  of  tide  is  about  6  feet  and  the  height  of  the 
deck  is  14  feet  2  inches  above  extreme  low  water. 

Special  precautions  were  taken  to  make  the  concrete 
durable  under  the  extreme  conditions  of  service.  The 
alumina  in  the  cement  was  limited  to  6.3%,  to  reduce  the 
chemical  action  of  the  sea  water  on  the  cement;  the  pro- 
portion for  all  concrete  below  high  water  was  made  1:  1J:  3 
to  resist  the  absorption  of  water  by  the  concrete  and  all 
concrete  surfaces  were  sheathed  from  low  water  to  2  feet 
above  high  water  with  two  layers  of  creosoted  2-inch 
plank  to  prevent  freezing  and  erosion  by  waves,  ice,  and 
driftwood.  The  piles  were 
designed  to  carry  100 
tons,  including  their  own 
weight  in  water.  They 
are  24  inches  square,  55 

t-f-  f         ,  i-i 

to  77  feet  long,  and  weigh 
from  12  to  23  tons.  The 
bracing  piles  were  cast 
with  a  camber  to  com- 
pensate for  the  bending 
of  the  piles  under  their 
own  weight.  A  12-ton 


/2"x8'xli"Creosoted 
Oak  Bearing  Pieces, 
2'c.toc. 


2"in 


Fig.  85.     Side  Detail,  Halifax  Pier. 


steam  pile  hammer,  especially  built  for  these  piers,  was 
used.  The  piles  are  spaced  10  feet  apart  in  the  bents 
and  the  bents  are  18  feet  apart  longitudinally.  There  are 
six  rows  of  shed  columns  and  under  each  column  there  is  a 
bracing  pile  and  one  or  two  extra  vertical  piles,  making 
33  vertical  and  6  inched  piles  in  each  bent.  The  upper 
portion  of  the  piles  was  cast  after  the  piles  were  driven. 
They  were  capped  with  girders  36  inches  deep,  carrying 
beams  24  inches  deep  and  an  8-inch  deck  slab. 

Especial  attention  was  given  to  transverse  stiffness,  owing 
to  the  great  unsupported  length  of  the  piles.  The  vertical 
piles  were  stiffened  by  a  bank  of  dredged  material  deposited 
around  them  and  by  the  inclined  piles. 

The  Havana  piers  are  164  feet  wide  and  660  and  680 


144 


WHARVES  AND  PIERS 


feet  long  and  are  located  in  water  from  12  to  40  feet  deep, 
on  a  bottom  consisting  of  15  to  20  feet  of  soft  mud  over- 
lying sand  or  clay.  The  range  of  tide  is  only  18  inches 
and  the  deck  was  elevated  only  5  feet  3  inches  above  mean 
low  water  to  have  it  conform  to  the  level  of  the  marginal 
street.  The  two-story  concrete  sheds  are  carried  on 
columns  spaced  about  20  by  30  feet  apart. 

The  extraordinarily  low  elevation  of  the  deck  required 
for  these  piers  presented  peculiar  difficulties  in  the  design, 
and  the  problem  was  solved  by  supporting  the  deck  slab 


b^-U44 

^Tm  ^*3? 


Part  Transverse  Section  parf  Longitudinal  Section 

Fig.  86.     Reinforced  Concrete  Pile  Piers,  Havana,  Cuba. 

on  wide  shallow  beams  carried  on  clusters  of  piles  located 
under  the  shed  columns.  The  clusters  contained  from  four 
to  eighteen  piles  and  were  capped  with  reinforced  concrete 
3^  feet  thick,  including  the  thickness  of  the  slab.  The  caps 
measured  from  7  by  8J  feet  to  20  by  24  feet  in  area.  The 
longitudinal  beams  were  15  and  18  inches  thick  and  11 
feet  wide  supported  on  recesses  in  the  sides  of  the  caps 
and  the  transverse  beams  were  cantilevers  7  feet  wide. 
The  deck  slab  averaged  12  inches  in  thickness.  Fig.  86 
shows  typical  pile  clusters  and  sections.  In  Havana 
Harbor  there  is  little  or  no  current  and  the  close  spacing  of 
the  piles  and  pile  clusters  was  unobjectionable.  The  piles 
were  16,  18,  and  20  inches  square  and  from  45  to  85  feet 
in  length,  with  a  maximum  weight  of  17  tons.  A  notable 


PIERS  145 

feature  was  that  they  were  reinforced  for  bending  stresses 
in  one  plane  only,  in  order  to  reduce  the  amount  of  steel 
to  a  minimum.  Pipes  were  cast  in  the  concrete  at  the 
proper  places  for  attaching  the  lifting  ropes,  and  the  piles  were 
kept  with  the  proper  side  uppermost  until  they  were  raised 
to  the  vertical  position.  Driving  the  piles  with  a  water 
jet  proved  unsuccessful  and  they  were  driven  with  a  six-ton 
steam  hammer  at  the  rate  of  about  ten  in  a  day.  Fifteen 
tons  dead  load  and  25  tons  live  load  were  allowed  on  a 
pile  and  the  bearing  power  was  determined  by  loading 
numerous  test  piles. 

Another  large  pier  on  concrete  piles  in  San  Francisco 
was  begun  in  1914.  It  is  975  feet  long  on  one  side  and 
817  on  the  other  and  200  feet  wide.  The  depth  of  water 
is  from  41  to  57  feet.  The  most  notable  feature  of  this 
pier  is  the  extraordinary  length  of  the  piles,  which  have  a 
maximum  of  106  feet  in  the  outer  rows.  They  are  16,  18,  and 
20  inches  square  and  were  designed  for  a  load  of  40  tons  in 
addition  to  their  own  weight.  The  penetration  was  about 
35  feet,  ten  of  which  was  in  soft  material. 

Piers  on  Reinforced  Concrete  Columns. -- The  columns 
in  use  on  the  Pacific  Coast  have  been  developed  to  the 
present  successful  form  through  several  stages.  The  design 
grew  partly  from  a  method  of  protecting  wooden  piles 
which  was  considerably  used,  and  partly  from  the  steel 
cylinders  filled  with  concrete  previously  described.  The 
method  of  pile  protection  consisted  of  placing  a  wood-stave 
pipe  around  a  pile  after  it  had  been  driven  and  filling  the 
space  between  the  pile  and  the  pipe  with  concrete.  The 
concrete  deposited  in  this  manner  in  many  cases,  often  due 
to  depositing  the  concrete  in  water,  was  imperfect  and 
allowed  the  teredo  to  get  at  the  piles,  but  where  the  forms 
were  carefully  pumped  out  and  the  concrete  reinforced, 
success  was  obtained.  In  some  cases  such  protected  piles 
failed  because  the  mud  line  was  lowered  below  the  bottom 
of  the  casing  by  dredging  subsequent  to  the  completion  of 
the  structure. 


146  WHARVES  AND  PIERS 

The  first  step  was  to  use  a  wood-stave  cylinder  of  about 
3^  feet  in  diameter.  As  it  was  found  that  a  column  of  a 
diameter  sufficient  to  carry  the  vertical  load  did  not  have 
sufficient  area  to  give  the  required  bearing  on  the  bottom, 
the  foot  of  the  pile  or  column  was  enlarged  to  7  or  8  feet  in 
diameter.  The  method  of  construction  was  as  follows: 
a  wood-stave  pipe  with  a  cast-iron  bell  bolted  to  the  lower 
end  was  jetted  and  hammered  down  through  the  mud  into 
the  hard  bottom.  The  water,  mud,  and  sand  were  then 
removed  from  the  interior,  the  bottom  sealed  with  concrete, 
the  reinforcement  placed,  and  the  cylinder  filled  to  the  top 
with  concrete.  The  wooden  form  was  left  in  place.  A 
pier  in  which  the  concrete  for  the  columns  was  deposited 
through  the  water  was  destroyed,  owing  to  the  disintegration 
of  the  imperfect  concrete. 

The  next  step  in  the  development  was  by  the  use  of 
open,  cylindrical  steel  cofferdams  in  which  the  columns 
were  built.  Some  of  these  were  1\  feet  in  diameter  and 
60  feet  long,  weighing  about  20  tons.  They  were  driven 
by  floating  pile-drivers,  or  land  leads  of  enormous  size  and 
strength  supported  on  temporary  pile  trestles.  These  ma- 
chines were  used  to  operate  the  bucket  for  excavating  the  sand 
and  mud  from  the  cylinders  and  for  pulling  up  the  cylinders 
after  the  columns  were  cast,  also  for  operating  swinging 
leads  which  were  lowered  into  the  cylinders  for  driving 
wooden  foundation  piles,  which  were  necessary  where  the 
bottom  did  not  have  sufficient  supporting  power  without 
them.  The  cylinders  were  pumped  out  and  the  wooden 
forms  built  in  them.  The  concrete  was  deposited  by  means 
of  chutes,  and  was  tamped  into  place  by  a  man  inside  the 
forms.  The  steel  cylinders  were  then  withdrawn,  the 
forms  being  left  in  place  on  the  concrete  columns.  Some 
difficulty  was  found  in  keeping  these  cylinders  plumb  if 
the  mud  for  any  cause  moved  while  they  were  in  place,  and 
the  concrete  columns  had  to  be  braced  to  neighboring 
columns  as  soon  as  the  steel  cylinders  were  removed. 

In  some  cases  it  has  been  found  impossible  from  various 


PIERS  147 

causes  to  seal  the  steel  cylinder.  This  difficulty  was  over- 
come by  putting  a  wooden  bottom  in  the  form  and  suspend- 
ing it  above  the  water  in  the  pile-driver  leads,  hoisting  the 
concrete  to  the  top  of  the  form  and  lowering  the  completed 
column  down  through  the  steel  cylinder.  In  another  case 
the  bottom  of  the  steel  cylinder  was  made  detachable, 
filled  with  concrete  to  make  a  seal,  and  left  in  place  when 
the  upper  portion  of  the  cylinder  was  raised. 

In  comparing  the  pier  built  on  concrete  piles  with  that 
built  on  columns,  the  advantage  of  one  over  the  other, 
aside  from  the  cost,  which  may  be  favorable  to  either  plan, 
depending  on  the  local  conditions,  is  in  the  matter  of  brac- 
ing. The  columns  cannot  conveniently  be  braced  against 
horizontal  forces  except  by  shallow  knees  between  the 
heads  of  the  columns  and  the  deck  beams,  or  by  steel  braces 
fixed  to  collars  fastened  to  the  columns,  which  are  subject 
to  conditions  which  produce  a  maximum  amount  of  corro- 
sion. Such  piers  depend  on  their  weight,  the  stiffness  of 
the  columns,  and  the  shallow  knee  braces  to  resist  the  thrust. 
On  the  other  hand,  where  the  concrete  piles  are  used  bracing 
piles  can  be  driven  and  the  direct  resistance  of  the  bottom 
utilized.  Both  these  types  require  floating  derricks  of 
large  capacity,  or  huge  pile-drivers,  or  both,  for  handling 
the  piles  or  the  steel  cylinders  in  which  the  columns  are 
built. 

While  the  column  method  has  been  used  in  building 
several  large  piers  in  San  Francisco,  it  is  doubtful  if  it  is  as 
economical  as  concrete  piles  where  the  nature  of  the  bottom 
is  such  that  piles  can  be  driven.  Three  great  piers  have 
been  built  during  the  last  five  years  on  the  Atlantic,  one  at 
Halifax  on  rock  at  great  depth  and  two  at  Havana  on  soft 
bottom,  and  the  latest  pier  designed  for  San  Francisco  is 
now  being  built  on  concrete  piles  some  of  which  are  of 
unprecedented  length. 

An  early  example  of  the  type  of  pier  built  on  concrete 
columns  is  shown  in  Fig.  87.  Two  piers  Nos.  38  and  40 
were  built  on  this  plan.  In  these  piers  the  concrete  columns 


148 


WHARVES  AND  PIERS 


were  cast  in  a  wooden  form  with  an  enlarged  cast-iron 
bottom  section,  driven  by  jets  and  hammered  into  the 
impervious  clay  overlying  the  rock,  and  pumped  out  before 
the  concrete  was  put  in.  The  depth  of  the  clay  was  about 
40  feet  below  the  water.  These  piers  were  about  130  feet 
by  650  feet  and  the  cylinders  were  spaced  15  feet  each  way. 
The  columns  carried  steel  cross-girders  and  longitudinal 


Cylfnder 
Reinforcement 


643-3 jjfo  End  of  Pier 
629-J%"foC.L.ofLasfCo/. 

*o*     , 


Outer    End  I    KooT  Framing       Floor  Framiny 

Plan 

Fig.  87.     Pier  on  Reinforced  Concrete  Columns,  San  Francisco,  Cal. 

beams  encased  in  concrete  which  supported  a  reinforced 
concrete  slab  and  asphalt  and  brick  pavements.  They 
carried  single-story  sheds  built  with  steel  frames  and  con- 
crete walls  and  roofs. 

Later  piers  were  constructed  with  columns  built  in  steel 
cofferdams  similar  to  those  at  Ft.  Mason,  and  the  caps  and 
joists  were  of  reinforced  concrete  instead  of  steel.  A 
floating  pile-driver  with  118-foot  leads  was  used,  also  one 
90  feet  high  supported  on  falsework. 


PIERS  149 

The  three  piers  at  Ft.  Mason,  in  the  construction  of  which 
cylindrical  steel  cofferdams  referred  to  above  were  first 
used,  are  500  feet  long  and  81,  118,  and  81  feet  wide.  They 
are  in  a  locality  where  heavy  ground  swells,  swift  currents, 
and  strong  winds  rendered  the  use  of  floating  equipment 
impracticable  and  made  the  work  especially  difficult  and 
costly.  The  water  was  25  feet  deep  at  the  outer  end  of 
the  pier  and  the  depth  provided  alongside  was  31  feet. 
The  bottom  consisted  of  layers  of  sand  and  mud  to  a  depth 
of  from  70  to  90  feet.  The  columns  were  spaced  18 J  feet 
each  way  and  were  capped  with  steel  beams  encased  in 
concrete  carrying  a  reinforced  concrete  slab  supported  on 
beams  similar  to  the  pile  caps.  The  columns  were  4  feet  in 
diameter  above  the  bell  at  the  bottom  and  were  cast  in 
wooden  forms  which  were  built  in  open  steel  cylindrical 
cofferdams.  The  latter  were  placed  and  removed  by 
means  of  very  large  pile-driver  leads  86  feet  high,  supported 
on  a  temporary  pile  falsework.  Each  column  rested  on  7 
timber  piles  60  to  85  feet  long  driven  from  20  to  70  feet 
below  the  dredging  line,  and  cut  off  about  11  feet  above  it. 
They  were  driven  by  means  of  a  follower  in  a  steel  guide 
tube  40  feet  long  which  was  accurately  located  by  means  of 
a  template  and  removed  after  the  pile  was  driven.  The 
steel  cofferdams  were  used  after  attempts  to  place  the  forms 
without  them  had  been  found  very  difficult.  They  were 
8  feet  in  diameter  and  weighed  17  tons.  The  pile-drivers 
had  a  lifting  capacity  of  100  tons  to  provide  the  necessary 
power  for  pulling  the  cofferdams  out  of  the  mud.  The 
concrete  in  the  columns  was  mixed  in  the  proportion  of 
l:lf:3. 

A  pier  was  built  on  similar  principles  to  those  of  the  two 
preceding  examples  at  the  Navy  Yard  at  Charleston,  S.  C., 
in  1915  in  which  was  introduced  a  novel  feature  which 
permitted  the  inspection  of  the  concrete  in  the  columns. 
The  lower  portion  of  the  steel  cofferdam  5  feet  long  was 
fastened  to  the  upper  portion  by  means  of  bolts.  The 
enlarged  concrete  footing  surrounding  the  wooden  piles 


150  WHARVES  AND  PIERS 

was  cast  in  the  steel  cylinder  as  a  form.  Steel  forms  for 
the  column  were  then  set  on  the  concrete  footing  and  the 
column  poured.  The  forms  were  then  stripped,  the  concrete 
inspected,  and  the  bolts  holding  the  two  parts  of  the  cylinder 
taken  out  and  the  upper  portion  of  the  cylinder  removed, 
the  necessity  of  heavy  lifting  devices  for  pulling  the  cylinders 
out  of  the  mud  being  thus  done  away  with,  a  25-ton  float- 
ing derrick  being  sufficient.  The  cofferdam  cylinders  were 
from  42  to  52  feet  long  and  8  feet  in  diameter.  The  45- 
foot  piles  were  driven  with  extension  leads  and  a  40-foot 
follower. 

Several  piers  have  been  built  with  the  decks  supported 
on  concrete  columns  in  which  thin  shells  of  reinforced 
concrete,  cast  on  shore,  have  been  used  in  place  of  the 
wooden  forms  described  above.  These  had  the  advantage 
that  it  was  possible  to  inspect  the  surface  of  the  concrete 
exposed  to  the  action  of  the  water  and  to  reject  any  portion 
that  was  imperfect. 

One  of  two  built  at  Olongapo,  P.  I.,  in  1910  is  illustrated 
in  Fig.  88.  It  is  332  feet  long  by  45  feet  wide  and  is  located 
parallel  with  the  shore  with  the  outer  edge  in  25  feet  of 
water.  The  cylindrical  shells  are  30  inches  in  diameter,  2J 
to  3  inches  thick,  with  an  enlarged  lower  portion  to  enclose 
the  wooden  piles  which  support  them.  They  are  from  25 
to  30  feet  long.  The  concrete  deck  slab  was  supported  on 
steel  girders  and  beams  encased  in  concrete. 

The  construction  of  the  shells  was  accomplished  without 
the  use  of  a  core-form  by  using  a  sheet  of  wire  cloth  with  2| 
meshes  to  the  inch  fastened  to  the  inside  of  the  reinforcing 
hoops.  The  wire  cylinder  was  then  placed  inside  a  wooden 
exterior  mould  in  a  horizontal  position.  Mortar  was  then 
poured  into  the  mould  and  protruded  through  the  wire 
cloth  just  enough  to  make  a  key.  No  interior  form  was 
required  and  a  man  smoothed  the  mortar  on  the  inside  of 
the  wire  with  a  trowel.  The  shells  were  driven  from  2  to 
4  feet  into  the  sand  bottom  by  water  jets,  and  stay-lathed. 
A  concrete  seal  was  then  put  in  place  by  bottom  dumping 


PIERS 


151 


buckets,  the  shells  pumped  out,  and  the  interior  of  the 
cylinders  filled  with  concrete.  These  piers  were  braced 
transversely  with  diagonal  steel  rods  placed  by  divers. 

A  similar  pier  was  built  at  Puget  Sound  Navy  Yard  in 
1912.  Metal  lath  of  the  form  known  by  the  trade  name  of 
"Hy-rib"  was  used  for  the  shell  of  the  shaft  and  ^-inch 
square  wire  mesh  for  the  enlarged  bottom  portion.  The 
Hy-rib  was  plastered  with  mortar  and  the  balance  of  the 


M.H.W. 


ML.W 


£ita»ssg»*^fl* 

II     tr      //»•*/  Y      f  i     U      '] 


!  1 1|  i 
.! 


Fig.  88.     Marginal  Pier  with  Reinforced  Concrete  Columns,  Olongapo,  P.  I. 

shell  was  made  of  very  wet  mortar  poured  into  the  forms. 
Trenches  were  dredged  for  the  shells,  as  the  bottom  was  so 
full  of  old  piles,  boulders,  and  hard,  gravel  that  the  use  of 
the  water  jet  was  impracticable.  The  longest  cylinder 
was  39  feet  in  length.  Diagonal  braces  of  steel  rods  were 
used  to  give  transverse  strength  to  the  pier,  which  was 
only  60  feet  wide.  No  piles  were  used  under  the  columns. 
The  specification  allowed  alternate  bids  on  the  method  of 
constructing  the  cylinders  in  steel  cofferdams  or  wooden 
shells  and  the  above  was  chosen  in  preference  to  them. 


152 


WHARVES  AND  PIERS 


An  interesting  method  of  construction  of  a  pier  or  wharf 
on  concrete  columns  is  shown  in  Fig.  89,  which  illustrates 
a  marginal  wharf  platform  at  Iloilo,  P.  I.  In  this  case  the 
cluster  of  piles  was  surrounded  with  a  steel  shell  drum 
forced  down  into  the  bottom.  The  earth  around  the  tops 
of  the  piles  was  then  removed  by  a  diver  and  concrete 
deposited  in  the  drum  to  within  6  inches  of  the  tops  of  the 
piles  by  means  of  a  canvas  bag.  The  drum  was  then 


Section  at  Lower  Horizontal    Bars 


Fig.  89.     Wharf  Platform  on  Concrete  Columns,  Iloilo,  P.  I. 

filled  to  the  top  with  gravel  and  the  concrete  columns, 
which  were  cast  on  shore,  set  up  in  the  gravel.  Grout  was 
next  forced  into  the  gravel  through  a  one-inch  pipe  with  a 
funnel  on  its  top.  The  columns  were  hollow  and  when 
pumped  out  did  not  leak  and  showed  that  the  grouting  was 
perfect.  Philipino  divers  on  this  work  were  paid  only  $1.00 
a  day. 

At  Balboa,  Panama,  a  concrete  marginal  wharf,  708  feet 
long  and  55  feet  wide,  was  built  in  1911  on  large  cylindrical, 
reinforced  concrete  columns  driven  to  rock  at  a  depth  of 
60  to  70  feet  and  spaced  35  by  30  feet.  This  wharf  was 


PIERS 


153 


built  in  a  tidal  inlet  which  was  cut  off  by  a  cofferdam  and 
the  construction  carried  on  in  the  dry.  After  trying  various 
methods  it  was  decided  to  cast  the  cylinders  in  6-foot 
lengths  and  handle  them  by  means  of  a  locomotive  crane. 
The  lower  section  was  10  feet  in  outside  diameter  and  the 


6,1  Anchor  Koc/s 
Sleeve  Nuts 
anot  C.I.Washers 


Fig.  90.     Wharf  Platform  on  Concrete  Columns,  Balboa,  C.  Z. 

upper  portion  8  feet,  with  walls  one  foot  thick.  The  con- 
crete in  the  shells  was  mixed  in  the  proportion  of  1:  2:  4. 
The  vertical  reinforcing  rods  were  placed  in  holes  moulded 
in  the  shells  and  rods  were  connected,  at  each  joint  of  the 
latter,  by  sleeve  nuts.  The  interior  of  the  columns  was 
filled  with  1:  3:  5  concrete,  reinforced  with  old  rails,  after 
sealing  and  removing  the  water.  The  greater  part  of  the 
mud  and  clay  was  removed  by  hand  excavation,  as  water 


154  WHARVES  AND  PIERS 

jets  did  not  work  well  in  the  clay,  even  with  120  pounds' 
pressure  and  orange-peel  buckets  were  not  as  efficient  as 
hand  work.  The  work  being  performed  in  the  dry  per- 
mitted the  placing  of  heavy  transverse  and  longitudinal 
reinforced-concrete  braces  between  the  columns  below  low- 
water  level.  The  mean  range  of  tide  is  about  13  feet  at 
this  location  and  the  bottom  along  the  outside  of  the  wharf 
was  dredged  to  40  feet  below  mean  sea  level  after  the 
wharf  was  built. 

BLOCK-AND-BRIDGE  PIERS 

Two  masonry  piers  have  been  built  on  the  block-and- 
bridge  plan  in  New  York.  Pier  New  No.  1  was  begun  in 
1872  and  completed  in  1876,  and  as  it  was  the  first  pier  to 
be  seen  from  vessels  coming  from  the  sea,  its  design  was  of 
a  monumental  character.  It  is  453  feet  long  and  80  feet 
wide  and  is  formed  of  18  semicircular  concrete  arches  of 
11  feet,  6  inches  radius,  18  inches  thick  at  the  crown,  sup- 
ported by  cross-walls  5  feet,  6  inches  thick,  except  at  the 
outer  end  of  the  pier,  where  the  wall  is  12  feet,  6  inches 
thick.  These  cross- walls  are  built  of  concrete  blocks  made 
in  air  and  set  by  derricks  and  divers.  They  rest  on  beds 
of  concrete  deposited  by  means  of  buckets  in  weighted, 
wooden  forms  placed  on  the  rock  bottom,  which  is  from 
25  to  50  feet  below  the  water  surface.  The  sides  of  the 
pier  are  faced,  above  low  tide,  with  granite  about  two  feet 
thick.  This  structure  is  said  to  have  cost  $14.00  a  square 
foot. 

Pier  A  was  built  in  1885,  not  for  commercial  purposes, 
but  for  the  offices  of  the  Department  of  Docks.  The  deck 
is  of  concrete  arches,  one  foot  thick  at  the  crown,  supported 
on  longitudinal  steel  girders  resting  on  cross-walls  of  concrete 
blocks,  similar  to  those  in  Pier  1.  The  cross-walls  are  5 
feet,  6  inches  thick  at  the  bottom  and  4  feet,  9  inches  at 
the  top  and  are  spaced  35  feet  apart.  The  cost  was  about 
$11.60  a  square  foot. 

A  small  block-and-bridge  pier  was  built  near  Glen  Cove, 


PIERS  155 

N.  Y.,  for  a  yacht  landing.  In  this  case  the  blocks  were 
hollow,  reinforced  concrete  caissons  set  in  place  by  large 
floating  derricks  and  filled  with  sand.  The  bridges  were  of 
wood. 

SOLID-FILLED  PIERS 

Solid-filled  piers  may  be  divided  into  two  classes.  First, 
those  in  which  there  is  a  pile  platform  outside  of  the  retain- 
ing structure,  and  second,  those  in  which  there  is  no  such 
platform,  vessels  being  moored  directly  against  the  vertical 
or  nearly  vertical  face  of  the  retaining  wall.  The. former 
type  is  usually  the  cheaper  in  first  cost  and  most  of  the 
large  solid-filled  freight  piers,  except  the  narrow  ore  piers 
of  the  Great  Lakes,  are  of  this  type.  This  is  due  to  the 
fact  that  such  piers  are  usually  built  in  comparatively 
shallow  water,  permitting  the  use  of  a  wall  of  relatively 
small  section  with  the  bottom  sloping  from  the  wall  to  the 
edge  of  the  platform. 

An  example  of  filled-in  piers  built  with  the  idea  of  reducing 
the  first  cost  to  a  minimum  is  that  of  the  Bush  Terminal. 
These  piers  are  located  on  a  sand-and-gravel  bottom  with  a 
general  elevation  slightly  below  low  water.  The  main 
retaining  structure  is  a  line  of  wooden  sheet  piling  supported 
by  tie  rods  across  the  piers  and  a  bank  of  riprap  in  front, 
as  shown  in  Fig.  43.  The  filling  was  obtained  by  dredging 
the  slips.  The  wharf  platform  is  of  the  usual  New  York 
type  of  timber  construction.  These  piers  were  covered 
with  sheds  and  the  flooring  over  the  filled  portion  was  of 
plank  laid  on  wooden  sills  resting  on  the  filling.  They 
have  lasted  from  12  to  15  years  without  many  repairs 
except  where  they  were  damaged  by  fire.  The  wooden 
flooring  has  been  replaced  by  concrete  in  some  places  and 
some  of  the  piers  have  recently  undergone  extensive  repairs 
to  the  outer  portion  of  the  platform. 

A  design  for  similar  piers  adjoining  those  of  the  Bush 
Terminal  but  of  more  durable  construction  was  made  by  the 
New  York  Dock  Department,  as  shown  in  Fig.  91,  but 
was  abandoned  in  favor  of  the  design  shown  in  Fig.  70. 


156 


WHARVES  AND  PIERS 


A  solid-filled  pier  without  a  marginal  platform,  known  as 
Commonwealth  Pier  No.  6,  and  used  for  the  fishing  in- 
dustry, was  completed  in  1914  by  the  Board  of  Directors 
of  the  Port  of  Boston.  The  pier  is  1200  feet  long  and  300 
feet  wide.  The  fill  is  retained  by  a  granite  masonry  wall 
which  is  illustrated  in  Fig.  19. 

Two  notable  piers  are  being  built  at  Victoria,  B.  C., 
with  vertical  walls,  extending  35  feet  below  low  water, 
formed  of  concrete  caissons  on  a  rubble  mound  in  water 


Fig.  91.     Design  for  a  Solid-filled  Pier,  Brooklyn,  N.  Y. 

up  to  60  feet  deep.  The  wall  is  shown  in  Fig.  30.  These 
piers  are  800  feet  long  and  250  feet  wide,  with  a  300-foot 
slip  between  them. 

Another  large  pier  of  this  type  is  being  built  at  Halifax 
by  the  Canadian  Government.  It  is  the  first  of  a  group 
of  six  similar  piers  which  are  planned  for  a  railroad  and 
steamship  terminal.  The  wall  in  this  case  is  composed 
of  stacks  of  cellular,  pre-cast,  concrete  blocks  filled  with 
concrete  and  stone  which  are  described  on  page  63.  The 
choice  of  this  design  was  influenced  by  the  large  amount  of 
rock  to  be  disposed  of  from  the  excavation  of  the  slips  to 


PIERS 


157 


the  required  depth  of  45  feet,  and  of  materials  from  the 
large  cuts  required  for  the  construction  of  the  railroad 
leading  to  the  terminal.  Other  considerations  were  the 


Fig.  92.     Solid-filled  Ore  Pier  with  Wooden  Sheet  Piling,  Marquette,  Mich. 

ground  swell  and  waves  which  rendered  the  use  of  floating 
plant  difficult  and  uncertain. 

Several  of  the  solid-filled  coal  and  ore  docks  on  the  Great 
Lakes  have  been  described  in  Chapter  IV.  A  number  of 
these  piers  have  been  built  recently,  in  which  sheet  piling 
of  wood  or  steel  is  used  to  retain  the  filling  instead  of  the 
timber  cribs  formerly  used. 

Fig.   92  illustrates  one  at  Marquette,  Mich.,  in  which 


158 


WHARVES  AND  PIERS 


wooden  sheet  piling  is  used,  and  inclined  piles  are  added  to 
increase  the  stability.  The  ore  bins  and  their  supports 
are  of  reinforced  concrete.  A  feature  is  the  sheathing  of 
the  face  of  the  concrete  with  steel  plates  from  6  inches 
below  the  water  level  to  3  feet  above  it  to  prevent  disin- 
tegration by  frost  and  abrasion.  Fig.  93  shows  one  of 


A-*-, 


f -Sheer Piling 


Fig.  93.     Solid-filled  Ore  Pier  with  Steel-sheet  Piling,  Duluth,  Minn. 

more  recent  date  at  Duluth,  Minn.,  in  which  steel-sheet 
piling  retains  the  filling. 

In  these  narrow  piers  the  columns  supporting  the  heavy 
bins  are  supported  on  concrete  footings,  carried  on  wooden 
piles  cut  off  just  above  the  water  line.  These  footings  also 
form  the  exposed  facing  of  the  piers.  The  sheet  piling 
retains  the  filling,  the  only  function  of  which  is  to  stiffen 
the  piles  and  to  give  a  surface  on  which  to  deposit  the 
concrete.  The  sheet  piling  is  supported  at  the  tops  by  rods 
embedded  in  the  concrete  and  extending  from  side  to  side 
of  the  pier. 


CHAPTER   VI 
WHARF  AND   PIER  SHEDS 

SHEDS  IN  GENERAL 

THE  function  of  sheds  on  wharves  and  piers  is  to  shelter 
freight  and  passengers  from  the  elements  and  to  prevent  theft 


Fig.  94.     Inshore  Elevation,  Reinforced  Concrete  Construction,  Chelsea 
Pier  Sheds,  New  York,  N.  Y. 

of  merchandise.  They  are  usually  used  for  sorting  both  in- 
bound and  outbound  freight  and  for  its  temporary  storage 
while  in  transit  between 
the  vessel  and  the  ware- 
house, but  in  some  cases 
are  used  as  warehouses. 
The  general  features  of 
their  construction  are  not 
essentially  different  from 
those  of  similar  struc- 
tures not  located  on  the 
water  front  and  are  usu- 
ally regulated  by  the 
building  laws  of  the  cities 
in  which  they  are  built. 


Fig.  95.  Outshore  Elevation,  Sheet-metal 
Construction,  Chelsea  Pier  Sheds,  New 
York,  N.  Y. 


On  deep-pile  foundations   lightness  is  of    great   impor- 
tance  in    decreasing    the  cost,    and  on  piers   subject    to 


160 


WHARVES  AND  PIERS 


unequal  settlement  and  to  distortion  from  the  impact  of 
vessels  elasticity  is  essential. 

Pier  sheds  are  one  or  two  stories  in  height.     The  upper 


Fig.  96.     Inshore  End-33rd  St.  Pier  Shed,  Brooklyn,  N.  Y.,  Showing  Sheet- 
metal  Construction. 


Fig.  97.     Front  Elevation  of  Head-house    of    Hollow-tile 
and  Stucco,  Commonwealth  Pier  5,  Boston,  Mass. 


Fig.  98.     Outshore  End  of  Shed,  Commonwealth  Pier  5, 
Boston,  Mass. 

story  is  commonly  added  for  the  use  of  passengers,  but 
there  are  a  few  very  large  piers  equipped  with  two-story 
sheds  on  which  freight  is  handled  on  both  floors. 


WHARF  AND   PIER  SHEDS 


161 


The  inshore  ends  of  pier 
sheds  are  often  joined  to  bulk- 
head sheds,  extending  along 
the  bulkheads  on  each  side  of 
the  pier,  and  to  head-houses 
on  the  bulkhead  which  contain 
offices  and  are  in  many  cases 
two  or  more  stories  in  height. 
The  fagades  of  such  buildings 
as  well  as  the  outshore  ends 
of  the  pier  sheds  call  for  archi- 
tectural ornamentation  and 
embellishment  to  fit  the 
aesthetic  requirements  of  the 
structure  and  the  locality. 
Sheet  copper  or  galvanized 
iron  on  steel  frames  which  are 
more  or  less  elastic  are  fre- 
quently used  where  the  foun- 
dations are  liable  to  settle- 
ment, but  on  the  Chelsea  Piers 
in  New  York  the  face  wall 
shown  in  Fig.  94  is  of  con- 
crete reinforced  with  expanded 
metal  supported  on  steel  girts. 
As  this  wall  is  on  filled-in  land 
overlying  deep  mud,  settlement 
is  expected  and  the  wall  at 
the  ends  of  the  piers  and  the 
steel  frame  of  the  bulkhead 
sheds  are  arranged  so  that  they 
can  be  jacked  up  independently 
of  each  other  whenever  the 
necessity  may  arise.  The  de- 
tails of  this  arrangement  are 
shown  in  Figs.  100  and  101. 
Where  the  foundation  is  not 
liable  to  settlement,  brick, 
concrete,  cement  mortar  on 


162  WHARVES  AND  PIERS 

metal  lath,  and  hollow  tile  covered  with  cement  stucco 
have  been  used. 

The  equipment  of  pier  sheds  with  cargo-handling  devices 
is  described  in  Chapter  VIII.  In  this  connection  may  be 
mentioned  a  shed  of  the  Tehuantepec  Railway  which  has 
the  novel  feature  of  having  removable  hatches  in  the  roof, 
through  which  the  freight  is  hoisted  and  lowered  by  loco- 
motive cranes. 

A  number  of  piers  in  New  York  and  other  cities  have 
two-story  sheds  the  upper  deck  of  which  is  designed  for 
recreation  purposes  and  the  lower  deck  for  freight,  as 
illustrated  in  Fig.  102. 

FIRE-RESISTING  CONSTRUCTION 

Fire-resisting  construction,  though  it  increases  the  cost  and 
weight,  should  receive  most  careful  consideration  in  the  de- 
sign of  sheds  which  are  to  contain  large  quantities  of  valu- 
able freight.  Many  existing  sheds  on  both  the  Atlantic  and 
Pacific  coasts  are  built  entirely  of  wood,  but  in  recent  years 
there  has  been  a  tendency  to  use  only  incombustible  or 
fire-resisting  materials.  Unprotected  steel  frames  are 
sometimes  cheaper  than  those  of  wood,  but  do  not  last  as 
long  in  case  the  freight  takes  fire.  Sometimes  a  combina- 
tion of  the  two  is  economical,  as  at  Seattle,  where  a  two-story 
shed  has  timber  posts,  Bethlehem  I-beam  girders,  and 
deep  timber  joists.  Some  steel  frames  have  been  encased 
in  tile  to  render  them  fire-resistant,  but  the  increase  in 
weight  is  considerable  and  increases  the  cost  of  pile  founda- 
tions. The  steel  columns,  second-floor  trusses,  and  joists 
of  the  B.  A.  R.  R.  piers  in  Boston  are  protected  with  plaster 
board  which  is  comparatively  light  and  a  galvanized  sheet- 
iron  jacket  has  been  used  in  some  New  York  Piers.  The 
unprotected  steel  frame,  when  used  with  an  adequate  equip- 
ment of  automatic  sprinklers,  offers  some  solution  of  the 
problem,  but  to  build  a  really  fire-proof  shed  the  frame  of 
which  is  light,  elastic,  cheap  and  economical  presents  many 


WHARF  AND  PIER  SHEDS 


163 


H 


164 


WHARVES  AND  PIERS 


difficulties.  Reinforced  concrete  is  heavy  and  expensive 
and  requires  many  columns  at  frequent  intervals  which 
obstruct  the  handling  of  freight.  Plate  girder  construc- 
tion has  the  same  objec- 
tions and  is  uneconomical 
in  the  use  of  the  metal. 
This  problem  appar- 
ently has  been  solved  in 
large  steel  pier  sheds 
recently  completed  in  the 
Panama  Canal  Zone,  by 
covering  the  individual 
members  of  the  roof 
trusses,  longitudinal  trus- 
ses and  monitors  with 
cement  mortar  1^  inches 
thick.  All  the  members 
of  the  trusses  were  cov- 
ered except  the  upper 
chords  which  were  en- 
closed by  the  concrete 
roof  slabs.  Light  wooden 
platforms  on  wheels  were 
provided  for  the  work- 
men to  stand  on  in  per- 
forming the  work.  The 
steel  was  first  thoroughly 
cleaned  with  wire 
brushes  and  then  cov- 
ered with  expanded 


Vertical    Section 
Y  -Y. 


Vertical     Section 

x-x. 


Fig.  101.     Details  of  Concrete  Wail, 
Chelsea  Pier  Sheds,  New  York. 


metal,  fastened  with  wire. 

Wooden  troughs  were 
supported  under  the  horizontal  and  inclined  members  and 
filled  with  mortar,  the  mortar  over  the  vertical  legs  of  the 
angles  being  shaped  with  a  combined  trowelling  and  screed- 
ing  tool.  No  forms  were  used  on  the  vertical  members 
which,  together  with  the  joints  were  plastered  and  trowelled. 


WHARF  AND  PIER  SHEDS 


165 


The  cement  gun  was  tried  but  was  unsuccessful  because 
the  waste  due  to  the  small  size  of  the  truss  members  was 
Wooden  forms  for  the  entire  section  were  also 


excessive. 


Fig.  102.     Recreation  Pier,  New  York,  N.  Y. 
Commerce. 


Lower  Deck  used  for 


it'Morhr 


tried,  but  on  account  of  the  thinness  of  the  mortar  coat, 
could  not  be  entirely  filled. 

The  cost  of  the  fire  proofing  of  the  trusses  was  about  12 
cents  per  square  foot  of  floor  area  (see  ap- 
pendix), and  even  if  the  labor  should  cost 
much  more  than  it  did  at  Panama,  a  shed 
frame  of  steel  protected  in  this  manner        f 'Lumber J 
would,  in   many  cases,   be   cheaper  than  Fls- 103>  Fire-proof- 

.    /.       .    i  .1  n          ing  for  Steel  Shed 

reinforced   concrete   or  any  other   really      Frames,    Balboa, 
fire-proof  construction.  C.  Z. 

FRAMING 

Shed  posts,  except  those  located  in  the  walls,  form  a  seri- 
ous obstruction  to  the  movements  of  wagons  and  trucks 
and  should  be  as  limited  in  number  as  possible  on  piers  on 
which  such  vehicles  enter.  In  the  North  German  Lloyd 
piers  at  Hoboken,  N.  J.,  this  was  considered  to  be  of  suffi- 


166 


WHARVES  AND  PIERS 


cient  importance  to  warrant  the  extra  cost  of  suspending 
the  second  floor  from  the  roof  trusses  as  shown  in  Fig.  104. 
About  20  feet  is  an  ordinary  spacing  for  trusses.  This  fits 
ten-foot  spacing  of  pile  bents  and  gives  an  economical 
length  for  purlins.  Sheds  up  to  100  feet  in  width  are  fre- 
quently built  in  one  span.  For  those  of  125  feet  two  spans 
are  economical  and  for  150  feet  three  spans  give  a  good 
arrangement  of  posts. 

The  usual  clearance  under  roof  trusses  and  under  floor 
beams  in  two-story  sheds  varies  from  17  to  22  feet.     If 


Fig.  104.     North  German  Lloyd  Pier  Shed,  Hoboken,  N.  J. 

travelling  cranes  and  telpherage  machines  are  used  for 
handling  freight,  this  height  is  increased  by  from  10  to  15 
feet. 

A  quadrilateral  form  of  truss  is  the  most  economical  for 
roofs.  The  longitudinal  members  of  the  frames,  the  bracing 
of  the  end  walls,  and  the  diagonal  bracing  in  the  roof  are 
similar  to  those  of  other  structures  and  need  no  particular 
description. 

SIDE  COVERINGS 

The  materials  most  used  for  the  side  covering  of  sheds 
on  pile  piers  are  wood,  galvanized  sheet  iron,  and  reinforced 
concrete.  On  solid-filled  wharves  which  afford  good  founda- 


WHARF  AND  PIER  SHEDS  167 

tions  hollow  tile  and  reinforced  concrete  are  more  commonly 
used. 

Corrugated  galvanized  iron  is  cheap,  light,  elastic,  and 
incombustible.  When  exposed  to  the  air,  however,  it 
deteriorates  rather  rapidly  when  near  salt  water,  and  the 
greatest  care  should  be  taken  to  keep  it  covered  with  an 
impervious  and  unbroken  coating  of  paint.  Before  the 
paint  is  first  applied  the  galvanized  iron  should  be  carefully 
washed  with  an  alkali  in  order  to  insure  adhesion.  Even 
with  the  greatest  care  it  is  difficult  to  make  paint  stay  on 
it  for  any  length  of  time,  owing  to  the  formation  of  zinc 
chloride  on  the  surface  wherever  the  salt  air  reaches  the 
metal. 

Corrugated  iron  protected  on  both  sides  with  a, layer  of 
asbestos  felt  treated  with  asphalt  and  an  outer  layer  of 
asbestos  fabric  has  recently  been  placed  on  the  market. 
It  is  claimed  for  this  material  that  it  has  all  the  advantages 
of  galvanized  corrugated  iron  and  that  it  is  very  durable 
without  painting  and  requires  little  or  no  maintenance. 

The  use  of  wood  for  siding  is  objectionable  on  account  of 
the  exterior  fire  risk.  If  covered  with  sheet  metal  on  the 
outside  this  risk  is  diminished,  but  it  still  aids  the  spread  of 
interior  fires. 

ROOFING 

The  "tar  and  gravel"  type  of  roof  laid  on  wooden  plank 
has  many  advantages  over  other  materials  in  the  ease  and 
cheapness  with  which  it  can  be  constructed,  its  elasticity 
and  lightness,  and  its  resistance  to  fire  on  the  outside.  It 
has  one  disadvantage  in  that  unless  it  is  protected  on  the 
underside  it  will  aid  in  spreading  a  fire.  If  it  is  protected 
by  plastering  it  may  be  subject  to  dry  rot.  This  may  be 
prevented  by  the  process  known  as  vulcanizing  or  similar 
methods  of  preservation.  Such  protection,  however,  adds 
to  the  expense,  and  the  fire  risk  may  be  safeguarded  to  a 
certain  extent  by  automatic  sprinklers.  On  the  B.  &  A. 
R.  R.  piers  in  Boston  the  heavy  3-inch  roof  plank  are  pro- 


168  WHARVES  AND  PIERS 

tected  on  the  under  side  with  plaster  board.  Fire-retarding 
paints  are  also  of  some  assistance. 

Concrete  tile  is  fairly  light  and  has  a  pleasing  appearance, 
but  requires  a  steep  slope,  which  is  objectionable  in  wide, 
sheds  on  account  of  the  resulting  height  and  wind  stresses. 

Reinforced  concrete  is  heavy  and  inelastic  and  is  liable 
to  be  cracked  by  the  impact  of  vessels  on  an  elastic  pier, 
but  it  excels  in  fire-resisting  qualities  inside  and  out. 

Sheds  should  be  provided  with  a  cornice  along  the  sides 
to  form  a  gutter  and  prevent  the  rain  water  from  running 
off  the  edges.  Down  spouts  should  be  carried  inside  the 
building.  The  lower  portion  should  be  of  steel  pipe  to 
prevent  damage  from  wagons  and  trucks.  Cornices  should 
not,  however,  overhang  in  such  a  way  as  to  interfere  with 
cargo-hoisting  gear.  Sheds  are  sometimes  built  with  sloping 
sides,  which  is  of  some  advantage  in  this  respect,  but  such 
sloping  sides  reduce  the  storage  capacity,  do  not  permit 
the  use  of  sliding  doors,  and  are  unnecessary  except  for 
piers  for  the  accommodation  of  square-rigged  vessels. 

LIGHTING  AND  VENTILATING 

Sheds  should  be  well  lighted  and  ventilated.  The 
cheapest  method  of  attaining  the  result  is  by  the  use  of 
skylights  and  galvanized  iron  ventilators.  Monitor  sky- 
lights with  machinery  for  opening  and  closing  movable 
sashes  are  better  but  much  more  expensive.  Where  it  is 
not  necessary  to  provide  doors  extending  in  height  to  the 
eaves  of  the  shed  a  row  of  windows  just  under  the  eaves  is 
of  advantage.  As  wired  glass  in  metal  frames  is  one  of 
the  best  fire-resisting  materials  the  window  area  should  be 
as  large  as  possible. 

DOORS 

The  design  of  cheap  and  efficient  doors  for  the  sides  of 
pier  sheds  is  a  subject  of  considerable  difficulty.  For 
steamship  piers  it  is  necessary  to  have  the  doors  come 
opposite  all  the  hatches  in  the  vessels,  and  for  this  reason 


WHARF  AND  PIER  SHEDS  169 

nearly  all  recent  pier  sheds  have  doors  in  every  panel. 
Doors  for  freight  which  is  hoisted  in  and  out  of  steamships 
and  other  vessels  should  be  as  high  as  possible  to  allow  the 
merchandise  to  be  swung  inside  the  shed.  Those  for 
freight  handled  by  trucks  do  not  require  great  height. 
Doors  for  pier  sheds  should  be  capable  of  being  rapidly 
closed  by  one  man  in  case  of  fire,  showers,  or  heavy  winds. 
There  are  four  types  in  general  use:  horizontally  sliding, 
vertically  swinging,  vertically  lifting  and  folding,  and 
rolling. 

Horizontal  sliding  doors  are  the  simplest  and  cheapest. 
They  are  usually  made  as  light  as  possible,  with  wooden 
frames  covered  with  diagonal  sheathing  boards  protected 
on  the  outside  with  sheet  metal,  as  shown  in  Fig.  105. 
They  are  hung  on  tracks  with  ball  or  roller  bearing  hangers, 
and  where  the  doors  fill  every  panel  in  the  side  of  the  shed 
provision  must  be  made  for  one  door  to  pass  another. 
This  type  of  door  is  liable  to  jam  when  being  closed  in  a 
heavy  wind  unless  it  runs  in  a  groove  at  the  bottom  pro- 
vided with  rollers  to  prevent  friction;  and  such  grooves 
are  liable  to  interfere  with  freight-handling  trucks.  On 
account  of  the  necessary  lightness  of  construction  this 
type  is  not  very  durable  in  the  large  sizes.  For  openings 
20  feet  square  on  steamship  piers  such  doors  are  usually 
made  in  two  leaves  and  this  is  about  the  limiting  size  for 
this  type. 

Vertically  swinging  doors  may  be  of  similar  construction 
or  may  be  made  much  heavier  with  steel  frames  and  cover- 
ing. When  not  counterbalanced  they  should  not  reach  in 
one  piece  below  the  height  of  a  man  from  the  deck,  as  they 
are  liable  to  fall  and  cause  accidents.  The  lower  portion 
of  the  opening  should  be  closed  by  small  multiple  shutters 
or  by  a  flap  folded  back  on  the  upper  portion  of  the  door. 
Swinging  doors  which  reach  the  deck  have  also  the  disad- 
vantage that  they  cannot  be  opened  when  freight  is  piled 
against  them.  Large  vertically  swinging  doors  if  strong 
enough  to  be  durable  are  so  heavy  that  one  man  cannot 


170 


WHARVES  AND  PIERS 


raise  them  without  the  aid  of  counterweights  and  gearing, 
which  add  very  greatly  to  their  cost. 

An  elaborate  door  of  large  size  used  on  the  Chelsea  piers 


Dwarf  Doors  on/y 
where  specified 

*I5/  Guide  Roller 
^fjsTSWilcox  Wedge 

If**  Wearing  Sfrip' 
bofh  sides 

Sheafhing  fo  project 
in  1  "fop  and  sides  fo  form 
rabbet.  Ga/v.sfee/  fo  be  carried 
inside  and  lapped  over  2  " 

1 

Fig.  105.     Wooden  Door  for  Pier  Sheds. 

in  New  York  City  is  shown  in  Fig.  106.  The  upper  por- 
tion is  swung  up  by  means  of  a  fourfold  rope  tackle.  The 
lower  portion  is  raised  vertically  in  guides  at  the  sides 
by  means  of  counterweights  and  gearing  operated  by  a 
hand  chain.  It  is  not  connected  to  the  upper  portion,  but 


WHARF  AND  PIER  SHEDS 


171 


the  joint  between  the  two  parts  is  closed  by  a  hinged  flap. 
When  in  the  upper  position  the  lower  portion  overlaps  the 
upper  and  may  be  swung  up  with  it.  This  arrangement 
allows  (1)  the  entire  doorway  to  be  open  or  closed;  (2)  the 
upper  portion  to  be  closed  and  the  lower  open  for  the  passage 


172 


WHARVES  AND  PIERS 


of  men  with  hand  trucks;  and  (.3)  the  upper  portion  open 
for  light  and  air  and  the  lower  portion  closed  to  prevent 
theft  of  merchandise.  These  doors  are  used  in  every 
panel  on  the  sides  of  the  piers  and  those  in  adjacent  panels 


WHARF   AND   PIER   SHEDS  173 

do  not  interfere  with  each  other.  One  man  can  close  them 
but  cannot  raise  the  upper  portion  alone. 

Doors  to  lift  vertically  are  made  to  fold  when  raised,  as 
in  Figs.  107,  as  there  is  not  sufficient  headroom  in  pier 
sheds  to  make  them  in  one  piece.  Such  doors  may  be 
opened  when  freight  is  piled  close  against  them. 

Steel  rolling  doors  for  large  openings  formerly  had  many 
objections.  They  were  liable  to  rust  and  stick  and  failed 
when  attacked  by  fire.  They  have  been  greatly  improved 
in  recent  years  and  have  been  placed  on  many  piers  of 
recent  construction  where  the  openings  are  not  too  large. 

All  patterns  which  require  gearing  or  other  machinery  for 
operation  are  comparatively  expensive  and  form  a  large 
item  in  the  cost  of  a  shed. 

Wicket  or  dwarf  doors  for  the  passage  of  watchmen  and 
the  escape  of  men  in  case  of  fire  should  be  provided  at 
convenient  intervals. 

Doors  at  the  ends  of  the  sheds  are  usually  of  the  sliding 
type  divided  into  units  which  can  be  handled  by  one  man 
or  may  be  of  larger  size  and  operated  by  machinery. 

PROTECTION  AGAINST  DAMAGE  AND  ACCIDENT 

The  exterior  corners  of  sheds  should  be  protected  against 
damage  by  mooring  lines.  The  outside  of  lintels  and  door- 
posts should  be  similarly  protected  against  injury  by  hoist- 
ing lines,  and  the  protection  should  be  of  such  materials 
that  it  will  cause  a  minimum  of  wear  on  the  ropes. 

Exterior  walls  and  all  posts  and  doorways  require  pro- 
tection against  damage  from  wagons  and  hand  trucks. 
Wooden  sheathing  is  commonly  used  for  the  inside  of  cor- 
rugated iron  siding,  but  it  increases  the  amount  of  com- 
bustible material.  Wheel  guards  of  various  forms  are 
used  to  prevent  wagons  from  striking  doorposts  and  interior 
shed  posts. 

The  distance  between  the  side  of  the  pier  shed  and  the 
edge  of  the  pier  should  be  sufficient  to  provide  a  safe  space 


174  WHARVES  AND  PIERS 

for  handling  the  mooring  lines  of  vessels.  It  usually  varies 
from  one  to  six  feet.  There  should  be  some  sort  of  foot 
rail  on  the  edge  of  the  pier  to  prevent  men  from  slipping 
off.  In  New  York  it  is  customary  to  make  this  rail  or 
" backing  log"  one  foot  high,  but  this  interferes  in  many 
cases  with  gangplanks  and  freight  handling.  A  hand  rail 
should  be  placed  on  the  outside  of  the  shed  for  further 
protection  against  men  falling  overboard. 

EXAMPLES  OF  TYPICAL  SHEDS 

A  simple  form  of  truss  entirely  of  wood  for  a  pier  70  feet 
wide  is  shown  in  Fig.  108.     This  truss  is  built  of  planks. 

Roof  Covering  -5 lag/  <*  Cement  on  /£  T&  6  Boards 
Purlins  3  "*/?"-  26 j  ctoc  Alfernat    ~ 


Splicing  Piece  axtOx  6-0     , .6  Camber 


Fig.  108.     Wooden  Shed  Truss,  for  70  Foot  Wide  Pier,  N.  Y.  Dock  Co. 

It  has  the  advantage  that  the  lumber  can  be  obtained  in 
the  sizes  used  of  superior  quality  at  a  reasonable  price. 
The  large  amount  of  wood  surface  and  the  spaces  between 
members  of  the  chords  of  the  trusses  are  objectionable  on 
account  of  the  fire  risk.  The  sides  of  the  shed  were  made 
entirely  of  steel,  to  comply  with  a  local  building  law.  The 
trusses  are  spaced  20  feet  apart.  A  steel  truss  on  similar 
lines  is  shown  in  Fig.  109. 

A  two  story  pier  shed  with  timber  frame  recently  com- 
pleted at  Seattle,  is  illustrated  in  Fig.  110.  It  was  de- 
signed for  a  second  floor  live  load  of  300  pounds  per  square 
foot  and  30  pounds  dead  load.  A  maximum  fibre  stress  of 


WHARF  AND  PIER   SHEDS 


175 


1,600  pounds  was  allowed  for  the  timber  with  400  pounds 
per  square  inch  in  compression  across  the  grain.  A  fea- 
ture is  the  cast  iron  caps  on  the  columns  which  are  en- 


8x20  Box  Sky  light- Each  Jic/e 
'\/n  d/fernafe  Panels 


/a%  Felt  ana/ Aspha/f-  Ctmertt 
If  'Dressed Spruce  Boards 
Leaders  40/4parf: 


Fig.  109.     Steel  Shed  Truss  for  70  Foot  Wide  Pier. 


Fig.  110.     Two-story  Timber  Shed,  Seattle,  Washington. 

larged  at  the  top  to  increase  the  bearing  area  of  the 
beams.  This  design  was  chosen  in  competition  with  one 
of  steel  which  required  30-inch  I  beams  in  place  of  the  16 
inch  by  18  inch  trussed,  Douglas  fir  timbers.  It  was  esti- 
mated that  the  wooden  frame  would  save  20%  over  the 
steel,  and  that  it  would  last  for  20  years. 


176 


WHARVES  AND  PIERS 


Such  a  frame  as  this  would  probably  withstand  a  fire  in 
the  contents  of  the  building  fully  as  long  as  one  of  unpro- 
tected steel  though  the  size  of  the  timbers  in  the  roof  are 
rather  small  for  slow  burning  construction. 

Fig.  Ill  shows  a  very  economical  shed  for  a  150-foot  wide 
pier.  The  trusses  are  20  feet  apart.  Two  light  wooden 
sliding  doors  20  feet  high  are  used  in  each  alternate  panel. 

A  similar  truss,  but  of  quadrangular  form  with  cargo 
masts,  is  shown  in  Fig.  112. 

A  shed  with  steel  frame  and  reinforced  concrete  sides  and 


(Berts   20'  Apartj 

I    (Weight  of  Steel  Frame  2000  Ib.  per  lin.  ft  of  Sheet) 
A 


II  I 


Half      Section      of      Pier-Shed       Framing 

Fig.  111.     Pier  Shed  33d  St.,  Brooklyn,  N.  Y. 


M 


roof  built  on  a  pile  pier  on  deep  mud  bottom  is  illustrated 
in  Fig.  113. 

A  similar  shed  one  story  high  on  an  adjacent  pier  was 
arranged  so  that  the  walls  were  independent  of  the  floor 
and  could  be  jacked  up  in  case  of  settlement.  The  walls, 
however,  gave  considerable  trouble  from  cracking.  The 
interior  columns  and  the  floor  and  roof  beams  of  these 
sheds  were  not  protected  against  fire  in  any  way. 

Fig.  114  shows  the  sheds  on  the  reinforced  concrete 
pile  piers  at  Havana.  The  columns  and  roof  beams  are 
reinforced  with  rivetted  structural  steel  strong  enough  to 


WHARF  AND  PIER   SHEDS 


177 


support  the  forms  in  order  to  facilitate  erection.  The 
sides  and  roof  are  of  cement  mortar  on  metal  lath  with 
raised  ribs.  The  down  spouts  for  rain  water  were  placed 
in  the  centre  of  the  shed  columns. 


178 


WHARVES  AND  PIERS 


Fig.  113.     Pier  Shed  with  Steel  Frame  and  Concrete  Roof  and  Sides, 
D.  L.  &  W.  R.R.,  Pier  9,  Hoboken,  N.  J. 


of  Pier  No.t 


^^^z^^&ssft       ^1 

^'Sffrrups    ^\:   ;   i   j-nT)77  IteS^^ 

i.        <«.    ::.  !  -- :  .:/    jK       _l  *L  3ii>x  ^ 


U-^'..>l  > 

(Centra/  Bays)        &/ 
Cross- Sec+ions       of       Transverse       6irder 


Fig.  114.     Reinforced  Concrete  Pier  Shed,  Havana,  Cuba. 

An  unusual  form  of  shed  is  shown  in  Fig.  115.     In  this 
case  the  posts  were  placed  10  feet  from  the  sides  of  the 


WHARF  AND  PIER   SHEDS 


179 


building  and  sliding  doors  arranged  to  pass  each  other  were 

hung  from  the  eave-truss.     Grooves  formed  of  angle  iron 

were  placed  in  the  deck 

to  hold  the   lower  edges    **— — ^ 

of  the  doors. 

Fig.  116  shows  a  tim- 
ber truss  of  100  feet  span 
on  the  municipal  docks 
of  Los  Angeles,  Cal.,  also 
a  steel  truss  of  the  same  „. 

Fig.  115.     Sheds  on  Piers  40  &  41  E.  R., 

size  with  cargo  masts.  New  York. 

A  steel  shed  with  con- 
crete roof  and  siding   is  shown  in  Fig.  117.     The  trusses 
were  spaced  30  feet  apart. 


Section   of  Outer  Harbor 

Wharf  and  Shed 


Fig.  116.     Timber  &  Steel  Shed  Trusses,  Los  Angeles,  Cal. 

The  two-story  steel  sheds  on  the  Chelsea  piers  in  New 
York  are  illustrated  in  Fig.  118.     The  cargo  masts  are  of 


180 


WHARVES  AND  PIERS 


elaborate  construction  and  carry  a  foot  walk  for  men  to 

rig  the  hoisting  gear.     The  side  covering  was  of  galvanized 

corrugated  iron  and  the  roofs  were  of  felt  and  slag  on  plank. 

The  shed  on  the  large  concrete  pile  pier  at  Halifax  is 


2j  Concrete  S/c*b~ 
wTre  Mesh4"*/2'' 


-V 


*  i       Web  Members: , 
^}  D/agrona/^ti,  3x2j*£ 

N  Vertical - 
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''A/I  Web  Members: 


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Cross    Section 

Fig.  117.     Shed  with  Steel  Frame  and  Concrete  Sides  and  Roof,  Pier 
No.  38,  San  Francisco,  Cal. 


Fig.  118.     Two-story  Shed,  Chelsea  Piers,  New  York,  N.  Y. 

illustrated  in  Fig.  84.  This  shed  is  200  feet  wide  and  di- 
vided into  five  bays.  It  is  designed  for  a  live  load  of  500 
pounds  per  square  foot  on  the  second  floor  and  110  pounds 
on  the  roof.  The  roof  is  of  concrete,  on  which  is  laid  a  layer 
of  boards  and  a  felt  and  gravel  surface  finish.  The  bents 


WHARF  AND  PIER   SHEDS 


181 


are  spaced  18  feet  apart.  The  doors  of  the  sliding  pattern 
are  in  alternate  panels  in  the  upper  story,  but  are  continuous 
in  the  lower.  The  lower  columns  are  25  inches  in  diameter 
and  are  protected  at  the  bottom  with  |-inch  steel  plates. 


'CO 

I 


bC 
£ 


Expansion  joints  were  provided  in  the  roof  of  the  shed,  but 
not  in  either  the  upper  or  lower  decks. 

A  two-story  steel  shed  for  the  1000-foot  46th  Street  pier 
in  New  York,  shown  in  Fig.  118a,  although  it  may  be  of 
limited  interest  in  that  it  is  designed  for  the  latest  and  larg- 


182  WHARVES  AND  PIERS 

est  transatlantic  passenger  steamers,  contains  many  interest- 
ing details.  The  posts  are  spaced  20  feet  apart  longitudinally 
except  for  a  distance  of  400  feet  at  the  inner  end,  where  those 
in  the  rows  on  each  side  of  the  center  line  are  spaced  40  feet 
apart  in  order  to  reduce  the  obstruction  to  wagons  and 
trucks.  The  depth  of  the  soft  mud  in  the  outer  portion  of 
the  pier  rendered  the  40-feet  spacing  impracticable  except 
at  the  inshore  end.  The  interior  posts  are  32  feet  4  inches 
apart  transversely,  which  was  considered  sufficient  for  a 
driveway,  leaving  unobstructed  bays  about  50  feet  wide  on 
each  side.  The  second  floor  consists  of  a  reinforced  con- 
crete slab  supported  on  steel  beams.  Provision  is  made  for 
depressed  railroad  tracks  on  this  floor,  the  depression  being 
filled  with  a  temporary  wooden  platform,  as  there  is  no  rail- 
road connection  with  the  pier  at  present.  The  cargo  hoist 
girders  on  this  pier  are  of  structural  steel  supported  on  posts 
spaced  20  feet  apart  and  are  designed  for  two  five-ton  loads 
applied  five  feet  from  the  supports  with  100  per  cent  added 
for  impact.  Light  and  ventilation  are  afforded  by  ventila- 
tors and  skylights  instead  of  by  the  monitors  used  on  the 
Chelsea  piers. 


CHAPTER  VII 
EQUIPMENT  OF  WHARVES  AND   PIERS 

FENDERS 

FENDERS  have  two  functions:  one  is  to  prevent  injury  by 
abrasion  and  the  other  is  to  absorb  the  energy  of  impact  of 
vessels  coming  in  contact  with  the  wharf.  The  necessity 


Qcof. 

J.  ""p  -—-..-.-..»..........-.  £    _„„».. ....... ...... .....I.. ^| 

4BniisedtoKhorbol'1s,  \ 

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Section   A-B 
Fig.  119.     Fender  on  Concrete  Piers,  Havana,  Cuba. 

of  fenders  depends  somewhat  on  the  absence  or  presence 
of  waves,  swells,  and  currents  in  the  water  adjacent  to  the 
structures.  They  are  almost  universally  used  in  this 
country,  but  are  often  omitted  from  European  structures, 
particularly  in  the  wet  docks.  Wooden  pile  structures,  on 
account  of  their  elasticity,  need  only  protection  against 
abrasion,  but  on  inelastic  wharves  and  piers  of  steel,  stone, 
or  concrete,  compressible  fenders  to  prevent  damage  to  both 
vessel  and  wharf  are  usually  considered  necessary.  There 
are  some  examples,  however,  of  inelastic  piers  on  which  the 
fenders  are  compressible  only  to  the  extent  furnished  by 


184 


WHARVES  AND  PIERS 


timber  fixed  to  or  suspended  from  the  face  of  the  structure. 
Examples  are  those  shown  in  Figs.  19,  50,  80  and  119. 

Fenders  are  of  three  general  types,  —  fixed,  spring,  and 
floating.  Fixed  fenders  may  take  the  form  of  piles,  vertical 
or  horizontal  strips,  or  sheathing.  Horizontal  strips  of 
heavy  timber  should  be  interrupted  at  frequent  intervals 
with  vertical  chocks.  If  this  is  not  done  they  may  be 
ripped  off  by  tugs  and  similar  vessels  which  have  con- 
siderable sheer  and  projecting  guards  and  waling  strips. 

An  excellent  form  of  fender  for  the  sides  of  wooden  pile 


8x10"  Oak 


TT 


I    II 


Fig.  120.     Continuous  Tendering  for  Wooden  Piers. 

piers  is  shown  in  Fig.  2.  The  piles  may  extend  above  the 
deck  of  the  piers  if  required. 

Another  form  covering  the  entire  exposed  portion  of  the 
sides  of  wooden  piers  for  use  in  places  where  there  are  many 
car  floats,  scows,  and  other  square-cornered  vessels  which 
would  damage  the  fender  piles  ordinarily  used,  is  shown 
in  Fig.  120.  Such  fendering  should  always  be  put  on  with 
a  space  between  the  strips  in  order  that  persons  who  fall 
overboard  may  climb  out  on  them. 

The  standard  corner  fender  for  the  wooden  piers  of  the 
New  York  Dock  Department  and  the  rounded  corner  used 
for  piers  for  large  passenger  steamships  are  shown  in  Fig.  2. 


EQUIPMENT  OF   WHARVES  AND  PIERS        185 

Fenders  for  concrete  surfaces  are  shown  in  Figs.  31,  76, 
and  121. 


t-T> 


_Hor.    Section   A-B 


•x^  imr  —     ["— 

Fig.  121.     Fender  for  Concrete  Wall,  Oakland,  Cal. 


\-   Top  of  Mooring  ctnot  C/usfer  Piles 


A/ Beams  under 
Roof  Co/s.  have 
8  "*  *  "Cover  PL 
Top  c*naf  Bottom 


Detail    of    Haunch 

Fig.   122.     Spring  Fender  for  Concrete  Pier,  San 
Francisco,  Cal. 

A  spring  fender  supported  on  fender  piles  for  a  concrete 
pier  at  San  Francisco  is  shown  in  Fig.  122. 

It  was  found,  however,  that  the  creosoted  exterior  por- 


186 


WHARVES  AND  PIERS 


tion  of  the  fender  piles  was  rapidly  worn  off  by  vessels 
and  the  piles  destroyed  by  the  teredo.  This  required  such 
frequent  renewals  of  the  piles  that  the  suspended  spring 
fender  shown  in  Fig.  123  was  substituted  on  piers  of  recent 
construction. 

Floating  fenders  consisting  of  round  logs  or  rafts  built 
up  of  timber  are  more  suitable  for  masonry  walls  than  for 
pile  structures,  as  they  cause  rapid  wear  of  the  piles.  This 
is  particularly  undesirable  where  the  piles  are  creosoted,  as 
the  marine  borers  attack  them  as  soon  as  the  creosoted 


Fig.  123.     Suspended  Spring  Fender  for  Concrete  Pier,  San  Francisco,  Cal. 

exterior  portion  is  worn  through.  Examples  are  shown  in 
Figs.  35,  57,  68  and  90. 

Compressible  fenders  made  of  bundles  of  saplings  bound 
with  wire  are  used  on  the  large  concrete-pile  pier  at  Halifax. 

A  fender  consisting  of  a  row  of  spring  piles,  connected  by 
horizontal  wales,  located  about  a  foot  from  the  face  of  a 
concrete  wharf  wall  but  not  connected  to  it,  has  been  used 
in  some  places. 

On  the  composite  pile  pier  at  Port  au  Prince,  Haiti, 
which  is  more  or  less  elastic,  creosoted  fender  piles  sheathed 
above  water  with  8  inches  of  yellow  pine  were  used,  as  shown 
in  Fig.  78. 


EQUIPMENT  OF   WHARVES  AND  PIERS        187 


MOORING  DEVICES 

Devices  for  attaching  the  mooring  lines  of  vessels  to  a 
wharf  may  be  in  the  form  of  piles,  posts,  cleats,  or  rings. 
Mooring  posts,  belay  posts,  snubbing  posts,  bitts  and  bol- 
lards are  local  names  for  the  same  general  class  of  mooring 
fixture. 

These  fixtures  should  be  designed  for  use  with  hemp  or 
wire  ropes,  arranged  so  that  the 
lines  may  be  readily  attached  and 
detached,  and  made  of  materials 
which  will  not  be  easily  worn  out 
by  use  and  which  will  not  cause 
undue  wear  on  the  ropes.  The 
diameter  should  be  .large  so  as 
not  to  cause  sharp  bends  in  the 
lines.  Mooring  devices  should  also 
be  so  shaped  that  the  hawsers  of  a 
large  vessel  the  decks  of  which  may 
at  times  be  far  above  the  deck  of 
the  wharf  will  not  slip  off.  They 
should  be  capable  of  easy  replace- 
ment and  renewal  when  worn  out 
or  broken. 

Timber  piles,  driven  through  a 
properly  braced  opening  in  the 
deck  of  a  wharf  structure,  or  into  a  Fig.  124.  C.  I.  Mooring  Post, 

f°r  Piers'  New 


York  Dock  Dept. 


solid  fill,  are  easily  worn  out,  are 

.  .  J       . 

subject  to  decay,  and  are  usually 

not  sufficiently  cheaper  than  other  kinds  to  justify  their 

use  for  permanent  structures. 

Granite  has  been  tried  in  some  cases,  but  mooring  posts 
of  this  material,  while  they  have  a  handsome  appearance, 
are  expensive,  brittle,  and  difficult  to  replace  when  broken. 

Reinforced  concrete  has  also  been  used.  It  is,  unless 
protected  by  metal,  rapidly  worn  out  by  wire  ropes  and  it 
wears  out  the  rope. 


188 


WHARVES  AND  PIERS 


Cast  iron  and  cast  steel  are  the  most  suitable  and  most 
generally  used  materials  for  this  purpose. 

The  large  post  shown  in  Fig.  124  has  been  in  use  for 


Fig.  125.     C.  I.  Small  Bitt,  New  York  Dock  Department. 

the  outer  corners  of  piers  for  many  years  in  New  York. 
The  horns  were  added  to  prevent  the  slipping  off  of  the 
hawsers  of  very  large  vessels.  Mooring  posts  of  such 

great  height  are  unnecessary  except 
at  the  corners  of  piers,  where  it 
may  be  necessary  to  fasten  a  num- 
ber  of  lines  at  the  same  time. 
Posts  for  the  corners  of  piers  should 
b6  stronger  than  those  on  the  sides, 
ag  ex^ra  heavy  stresses  are  put 

Fig.  126.    C  I.  Mooring  Cleat,    Qn  them    in    docking   vessels.      The 
New  York  Dock  Dept.  _,.  °  ,    - 

small  bitts,  Fig.  125,   are  used  for 

the  sides  of  piers  and  are  suitable  for  all  but  the  very  largest 
steamships.  Cleats  of  the  pattern  shown  in  Fig.  126  are 
used  for  lighters,  tugs,  etc.  They  are  also  used  as  fair- 
leaders  in  connection  with  corner  mooring  posts,  as  shown 
in  Fig.  127. 


EQUIPMENT  OF   WHARVES  AND  PIERS        189 


A  mooring  or  " belay"  post  of  steel  plate  filled  with  rein- 
forced concrete  was  used  on  the  B.  &  M.  R.  R.  piers  in 


Fig.  127.     Corner  Mooring  Post  with  Cleat  used  as  a  Fair-leader. 

Boston.  Fig.  76  illustrates  a  form  of  "bollard"  common  in 
European  practice.  An  unusual  form  of  double  bitts  was 
designed  for  the  piers  re- 
cently built  in  San  Fran- 
cisco and  is  shown  in  Fig. 
123. 

An  excellent  form  of 
mooring  post  is  that  used 
on  the  concrete  wall  at 
Oakland,  CaL,  shown  in 
Fig.  128. 

Other  forms  are  shown  in 
Figs.  13,  18,  51,  and  77. 

The  usefulness  of  double  Fig  12g     Mooring  Post>  Oakland>  Cal 
posts  or  double  bitts  on  a 
wharf  is  not  apparent  where  the  mooring  devices  are  used 


190 


WHARVES  AND  PIERS 


simply  to  hold  a  line  in  the  end  of  which  a  loop  is  spliced  or 

tied.    Appliances  of  this  form  are  more  useful  on  the  vessels 

where  the  lines  are  handled,  adjusted  for  length,  and  made  fast. 

Mooring   rings   are   sometimes   placed   in   the   faces   of 


Fig.  129.     Wharf  Drop. 

masonry  walls  or  on  the  top.  They  are  not  to  be  recom- 
mended, as  they  are  clumsy,  inconvenient,  and  cause  sharp 
bends  in  the  hawsers  and  consequent  injury. 

WHAKF  DROPS 

Wherever   it   is   necessary   to   transfer   freight   between 
wharf  and  vessel  by  means  of  trucks  in  localities  where 


EQUIPMENT  OF  WHARVES  AND  PIERS        191 

there  is  a  considerable  rise  and  fall  of  the  water  surface, 
" wharf  drops"  or  movable  gangways  are  required.  These 
are  sections  of  the  deck  hinged  at  one  end  and  suspended 
from  overhead  frames  at  the  edge  of  the  wharf  so  that  they 
may  be  raised  or  lowered  by  hand-power  gearing  or  by 
electric  motors,  as  shown  in  Fig.  129.  It  is  evident  that 
if  more  than  one  of  these  gangways  is  to  be  used  on  a  vessel 
at  the  same  time  they  must  be  located  to  match  the  side 
ports  of  the  vessel.  These  gangways  may  be  fitted  with 
electrically  driven  chains  equipped  with  projections  to 
engage  the  axles  of  freight  trucks  and  assist  them  up  the 
grade,  as  described  in  Chapter  VIII. 

PAVEMENTS 

Pavements  for  wharves  should  offer  a  good  foothold  for 
men  and  horses.  They  should  be  smooth  where  trucks  for 
moving  freight  are  used.  They  should  be  non-absorbent, 
so  that  water  and  other  liquids  cannot  soak  into  them. 
The  wear  on  wharves  where  there  are  many  horse-drawn 
trucks  is  frequently  concentrated  in  narrow  lines,  and  on 
many  wharves  the  traffic  is  so  dense  that  pavements  wear 
very  rapidly.  Such  pavements  should  therefore  be  easily 
removed  and  repaired  when  worn  out.  Those  for  pile 
wharves  should  be  light  in  weight. 

The  substances  used  for  pavements  and  wharves  are 
plank,  concrete,  sheet  asphalt,  wood  block,  brick,  asphalt 
block,  and  granite  block. 

Plank  is  the  least  durable  material,  but  it  is  absorbent, 
and  where  there  are  very  many  horse-drawn  trucks  it  acquires 
an  offensive  odor.  It  is,  however,  light,  elastic,  and  low  in 
price.  Pacific  Coast  white  cedar  is  said  to  be  superior  to 
other  woods  for  this  purpose.  Vertical  grain  fir  is  also 
used  on  the  Pacific  Coast.  In  New  York  3-inch  yellow  pine 
sheathing  requires  complete  renewal  after  six  years.  In 
San  Francisco  Douglas  fir  is  said  to  have  lasted  only  one 
year  and  white  cedar  two  years. 

Concrete  is  low  in  first  cost,  but  it  is  very  difficult  to 


192  WHARVES  AND  PIERS 

make  it  durable  where  there  is  much  horse  trucking.  The 
grinding  action  of  heavy  loads  on  narrow-tired  wheels,  due 
to  the  frequent  turning  necessary  in  manoeuvring  wagons 
in  the  narrow  roadways,  is  particularly  destructive  to  it. 

A  light  sheet  asphalt  pavement  on  a  concrete  base  has 
been  found  very  satisfactory.  It  is  cheap,  elastic,  and  can 
be  easily  repaired.  In  New  York  a  pavement  2|  inches 
thick  costs  only  from  10  to  15  cents  a  square  foot  with  a 
five-year  maintenance  guarantee.  An  objection  to  such 
pavements,  however,  is  that  they  are  liable  to  be  indented 
in  warm  weather  by  sharp  objects,  such  as  the  ends  of  casks 
and  barrels.  Sheet  asphalt  pavements  the  surface  of  which 
is  composed  of  broken  stone  and  sand  are  less  subject  to 
this  defect  than  those  made  with  sand  only. 

Pavements  of  creosoted  wood  blocks  have  been  used  with 
great  success  on  many  piers.  They  are  light  and  can  be 
laid  directly  on  either  plank  or  concrete  foundations,  but 
the  first  cost  is  very  high,  and  where  there  is  little  traffic  the 
blocks  are  said  to  shrink  and  become  loose.  In  Philadelphia 
the  price  is  about  double  that  of  asphalt. 

Brick,  asphalt  blocks,  and  granite  blocks  are,  on  account 
of  their  weight,  more  suitable  for  solid-filled  wharves  than 
those  on  pile  foundations.  They  are  somewhat  difficult  to 
repair  satisfactorily  when  unevenly  worn. 

RAILROAD  TRACKS 

Where  it  is  necessary  to  have  railroad  tracks  on  a  pier 
they  may  be  placed  in  the  middle  or  at  the  edge  and  may  be 
placed  at  the  elevation  of  the  surface  or  depressed  so  that 
the  floors  of  the  cars  are  on  a  level  with  the  deck.  They 
should  be  arranged  so  as  to  waste  as  little  wharf  space  as 
possible  and  to  produce  a  minimum  cost  in  handling  the 
freight. 

Depressed  tracks  have  the  great  disadvantage  that  they 
form  a  barrier  against  the  movement  of  trucks.  They 
may  be  crossed  on  movable  bridges,  but  the  latter  interfere 
with  the  shifting  of  cars.  Where  motor  trucks  are  used 


EQUIPMENT  OF  WHARVES  AND  PIERS       193 

for  handling  freight,  portable  platforms  and  ramps  may 
be  used  to  enable  trucks  to  enter  box  cars,  instead  of  de- 
pressing the  tracks,  and  where  overhead  cranes  or  telephers 
serve  the  cars,  portable  platforms  will  provide  all  the 
advantages  of  depressed  tracks.  The  space  occupied  by 
depressed  tracks  cannot  be  used  for  any  other  purpose, 
while  if  the  tracks  are  at  the  level  of  the  top  of  the  wharf 
the  space  occupied  by  them  when  not  filled  with  cars  can 
be  used  for  trucks  or  storage. 

A  double  track  in  the  middle  of  a  pier  wastes  less  deck 
room  than  a  track  on  each  side  and  has  the  advantage  of 
permitting  the  installation  of  cross-overs  between  the 
tracks  which  facilitate  the  shifting  of  the  cars.  A  single 
track  on  each  side  of  the  pier  can  seldom  be  kept  full  of 
cars,  and,  even  if  not  depressed,  the  space  it  occupies  on  a 
shedded  wharf  cannot  be  used  for  other  purposes  when  not 
occupied  by  cars. 

If  the  tracks  are  placed  on  the  sides  of  a  pier  there  is 
some  saving  in  the  width  of  the  shed  required. 

It  is  seldom  practicable  to  transfer  general  cargo,  with 
the  appliances  in  use  at  present,  directly  from  car  to  ship  or 
from  ship  to  car.  In  the  first  case  a  double  track  on  the 
side  of  the  wharf  is  required  with  frequent  cross-overs  if 
more  than  one  hatch  is  to  be  loaded  at  the  same  time  and 
the  loading  is  not  to  be  interrupted  by  the  shifting  of  the 
empty  cars.  It  does  not  pay  to  run  a  travelling  crane 
longitudinally  on  a  wharf  for  transporting  freight  from  the 
end  of  a  string  of  cars  to  the  vessel's  hatch,  as  so  much  time 
is  lost  in  travelling  that  it  is  usually  cheaper  to  keep  the 
crane  stationary  and  transport  the  goods  from  the  car  to 
the  machine  by  hand  or  motor  trucks.  In  unloading  a 
vessel  the  freight  nearly  always  has  to  be  sorted  before  it 
can  be  put  in  the  cars. 

Direct  transfer  between  car  and  vessel  is  much  more 
common  in  Europe  than  it  is  in  this  country.  This  is 
probably  due  to  the  nature  of  the  rolling  stock.  The  cars 
used  abroad  are  very  much  smaller  than  ours  and  open  cars 


194  WHARVES  AND  PIERS 

or  what  are  termed  "  gondolas"  in  this  country  are  used  for 
everything  but  very  small  and  valuable  packages,  the 
freight  being  protected  from  the  weather  by  tarpaulins. 
Our  box  cars  are  not  adapted  for  rapid  loading  and  unload- 
ing with  cranes  or  telephers,  but  it  is  possible  that  as  the 
demand  for  the  use  of  such  machines  increases,  box  cars  will 
be  made  with  removable  roofs  so  that  they  may  be  loaded 
and  unloaded  without  the  use  of  platforms  or  hand  trucks. 
In  New  York  there  is  considerable  direct  transfer  of 
freight  between  cars  and  lighters.  It  is  to  a  great  extent 
limited,  however,  to  machinery  and  similar  goods  carried  on 
flat  or  gondola  cars.  Special  piers  are  provided  for  this 
purpose,  equipped  with  several  lines  of  tracks  and  with 
locomotive  revolving  cranes  or  gantry  cranes  of  the  pattern 
shown  in  Fig.  140. 

FIRE  PROTECTION 

The  fire  risk  on  freight  piers  is  considerable,  both  external 
and  internal.  Fires  on  wooden  wharves  have  frequently 
resulted  in  the  total  destruction  of  the  structures  them- 
selves, the  freight,  and  the  vessels  lying  alongside.  There 
have  been  cases,  however,  where  the  sheds  and  freight 
have  been  destroyed  and  the  wooden  pier  decks  were  not 
even  burned  through.  The  principal  risk  is  from  the  cargo, 
which  is  often  of  much  greater  value  than  the  pier  and 
shed,  so  that  it  is  of  more  importance  to  safeguard  the 
cargo  from  fire  than  the  wharf  structures.  Among  the 
most  usual  known  causes  are  defective  electric  wiring, 
spontaneous  combustion  of  baled  cotton,  fires  on  vessels 
alongside,  and  burning  oil  floating  on  the  surface  of  the 
water. 

Many  wharves  have  been  constructed,  not  only  without 
any  regard  whatever  to  fire  protection  but  in  such  a  way 
as  to  increase  the  risk  in  many  unnecessary  ways,  and  it  is 
only  within  the  last  few  years  that  much  attention  has  been 
given  to  this  subject. 

The  general  requirements  for  protection  against  fire  are, 
for  piers  and  sheds,  as  follows: 


EQUIPMENT  OF   WHARVES  AND  PIERS        195 

1.  The  division  of  the  space  in  the  sheds  and  under  the 
deck  of  the  pier  by  fire  walls,  with  self-closing  fire-proof 
doors  in  all  openings,  in  order  to  confine  a  fire  to  a  com- 
paratively small  space  and  to  permit  of  its  being  extinguished 
by  the  firemen.     This  is  the  most  important  of  all  the 
requirements. 

2.  The  use  of  automatic  sprinklers  properly  maintained 
and  inspected,  also  of  water  curtains  along  the  outside  of 
pier  sheds. 

3.  The  use  of  materials  which  are  not  destroyed  by  fire, 
such  as  reinforced  concrete  and  steel  encased  in  concrete 
or  tile;  or  which  resist  fire,  such  as  heavy  timber  and  the 
elimination  of  destructible  materials  such  as  unprotected 
steel  frames,  wooden  beams,  joists,  and  purlins  of  small 
section,  and  wooden  siding. 

4.  The  use  of  automatic  alarms. 

5.  The    installation    of    fire    buckets,    chemical    extin- 
guishers, and  hose. 

6.  The  elimination  of  openings  as  far  as  possible  in  the 
upper  floors  of  sheds  which  are  more  than  one  story  high. 
The  enclosure  of  all  elevator  shafts,  stairways,  and  other 
openings  with  fire-proof  walls,   equipped  with   self-closing 
fire-proof  doors. 

Fire  Walls.  -  -  The  huge  undivided  space  in  large  pier 
sheds  has  often  acted  as  a  furnace  when  filled  with  freight. 
If  the  fire  starts  with  the  doors  open  at  both  ends  it  spreads 
with  incredible  rapidity  —  so  fast  that  men  at  work  on  the 
piers  have  no  time  to  escape  except  by  jumping  overboard. 
The  heated  gases  sweep  through  the  shed  and  set  every 
combustible  thing  on  fire.  If  the  fire  once  gets  under  way, 
buckets,  extinguishers,  and  hose  cannot  be  used.  The  shed 
if  not  built  of  fire-resisting  materials  usually  collapses  in  a 
few  minutes,  the  roofing  makes  the  efforts  of  the  firemen  of 
little  use,  and  the  fire  usually  burns  itself  out. 

To  make  fire  walls  effective  the  openings  in  them  should 
be  as  few  and  as  small  as  possible  and  should  be  fitted  with 
self-closing  fire-proof  doors.  Such  walls  in  the  sheds  are 


196  WHARVES  AND  PIERS 

inconvenient,  as  they  interfere  with  the  handling  of  the 
freight  and  are  strenuously  objected  to  by  most  pier  super- 
intendents, but  these  objections  are  being  overcome  and 
the  use  of  walls  is  rapidly  increasing. 

The  use  of  thin  wooden  deck  joists  and  of  pile  caps  and 
rangers  or  stringers  in  pairs,  separated  by  a  narrow  space, 
are  particularly  objectionable  as  far  as  the  fire  risk  is  con- 
cerned. Such  caps  and  rangers  afford  the  best  possible 
conditions  for  maintaining  a  fire  under  the  deck  of  a  pier 
and  are  most  difficult  to  reach  with  fire  hose.  To  offset 
this  objection  the  New  York  Dock  Department  places 
reinforced  concrete  fire  walls  about  300  feet  apart  in  their 
wooden  piers,  extending  from  the  deck  to  low  water  and 
from  side  to  side  of  the  pier,  with  hatches  in  the  deck  at 
intervals  of  about  50  feet  to  provide  access  for  firemen  to 
the  space  underneath.  Such  walls  help  to  confine  a  fire 
under  the  deck  of  a  pier  to  a  small  area. 

Sprinklers.  -1  The  automatic  sprinkler  is  the  best  and 
most  economical  method  of  prevention  and  control  of  fires 
on  piers  and  wharves  and  costs  only  about  10^  a  square 
foot  of  floor  space.  The  installation  and  maintenance  in 
efficient  condition  of  this  device  in  a  pier  shed  is  of  more 
importance  than  the  construction  of  the  shed  of  materials 
indestructible  by  fire,  as  the  sprinklers  protect  the  freight 
as  well  as  the  shed,  even  if  the  latter  is  built  of  materials 
which  do  not  resist  fire.  It  is  the  freight  which  usually 
furnishes  the  greater  part  of  the  fuel,  and  often  causes  a 
greater  money  loss  than  the  shed.  Even  if  the  shed  is  of 
the  best  fire-resisting  construction  the  sprinklers  should  in 
no  case  be  omitted  if  freight  is  to  be  stored  in  it  at  any  time. 

It  is  only  of  late  years  that  sprinklers  have  been  used  on 
piers  and  their  use  is  spreading  but  slowly.  This  is  due  in 
some  instances  to  lack  of  capital  and  perhaps  some  explana- 
tion may  be  found  in  the  way  in  which  the  interest  in  fire 
protection  is  divided  among  the  parties  which  own  and 
use  the "  pier.  For  example,  one  company  may  own  a  pier 
and  rent  it  to  a  steamship  company  which  carries  freight 


EQUIPMENT  OF   WHARVES  AND  PIERS        197 

owned  by  individual  shippers.  The  latter  pay  for  the 
insurance  on  the  cargo,  which  is  carried  by  the  steamship 
company  and  is  included  in  the  freight  rates,  and  they 
supply  the  greater  part  of  the  fuel  in  case  of  fire.  The 
steamship  company  which  leases  the  pier  maintains  and 
inspects  the  sprinkler  system,  which  is  owned  by  the  party 
who  owns  .the  pier.  The  owner  is  interested  in  the 
possible  loss  of  income  if  the  pier  is  burned,  but  as  it  is 
difficult  for  him  to  make  sure  of  the  proper  care  and  in- 
spection of  the  apparatus,  without  which  it  is  worthless,  he 
hesitates  to  spend  money  on  the  installation.  The  interest 
of  the  steamship  company  lies  in  the  decrease  of  the  risk  of 
destruction  of  freight  and  vessels  lying  alongside  the  pier, 
and  in  the  decrease  of  rent  which  includes  the  insurance  on 
the  pier,  and  in  a  possible  decrease  in  the  insurance  of  the 
freight. 

The  shipper  is  only  slightly  interested,  as  the  difference 
in  freight  rates  due  to  the  sprinklers  on  a  pier  may  be  com- 
paratively unimportant. 

It  is  difficult  to  understand  why  the  owners  and  lessees 
of  piers  do  not  see  the  advantage  of  sprinklers,  which  is 
shared  by  both,  in  a  stronger  light  and  why  any  difficulties 
in  maintenance  of  the  apparatus  cannot  be  obviated  by 
clauses  in  the  leases  requiring  proper  .maintenance  and 
inspection  by  the  companies  which  make  a  specialty  of 
such  work  and  are  thoroughly  reliable. 

The  best  practice  requires  that  a  sprinkler  system  should 
be  supplied  with  water  from  at  least  two  different  sources, 
one  of  which  should  be  an  elevated  tank  properly  protected 
against  frost.  The  other  supply  should  be  from  the  city 
mains,  if  available,  or  from  fire  pumps.  Connections 
should  be  supplied  at  both  ends  of  the  pier  for  fire  engines 
and  fire  boats.  The  dry-pipe  system  of  water  distribution 
is  necessary  on  piers  where  water  in  the  pipes  is  subject  to 
freezing.  Cornice  sprinklers  or  " water  curtains"  should 
be  installed  on  the  outside  of  the  sheds  for  protection  against 
exterior  fires,  such  as  burning  ships.  Perforated  pipes 


198  WHARVES  AND  PIERS 

with  connections  for  fire  boats  and  fire  engines  have  in 
some  cases  been  placed  under  the  decks  of  wooden  piers. 

Roof  Hydrants.  —  Roof  hydrants  are  useful  for  fighting 
fires  on  ships  and  lighters  lying  alongside  a  shedded  pier. 

Fire-resisting  Materials.  -  -  The  use  of  fire-resisting 
materials,  such  as  reinforced  concrete  or  steel  encased  in 
hollow  tile  or  concrete,  makes  a  pier  shed  so  heavy  that  it 
increases  the  cost  of  a  pile  foundation  very  considerably 
and  for  this  reason  structures  having  fire-proofed  walls, 
frames,  and  roofs  are  unusual  on  pile  piers.  Their  number, 
however,  has  increased  considerably  in  recent  years. 

Unprotected  steel  roof  trusses  or  second-story  floor 
beams,  though  incombustible,  will  collapse  in  a  very  short 
time  if  subjected  to  a  fire  in  the  freight  under  them,  as  has 
happened  in  many  instances.  Such  collapses  have  often 
resulted  in  the  fire  burning  itself  out  as  stated  above. 

Heavy  wooden  columns  and  trusses  will  stand  up  much 
longer  in  a  fire  than  unprotected  steel,  but  are  usually  so 
reduced  in  section  after  a  fire  that  they  have  to  be  replaced. 
They  are  useful  in  that  they  are  slow  burning  and  permit 
of  effective  work  by  firemen  in  saving  the  cargo. 

The  sides  of  a  shed  should  always  be  of  incombustible 
material  and  all  glass  in  windows  and  skylights  should  be 
wired. 

Piers  which  are  constructed  of  wood  between  the  water 
and  the  deck  are  subject  to  fire  risk  from  vessels  alongside 
and  from  floating  burning  materials.  They  may  be  pro- 
tected from  this  risk  by  sheathing  on  the  outside,  provided 
that  sufficient  ventilation  is  provided  under  the  deck  to 
prevent  rot,  as  has  been  described  in  previous  chapters. 

Automatic  Fire  Alarms.  —  Automatic  fire  alarms  which 
operate  from  local  application  of  heat  should  be  used  in 
sheds  to  give  notice  of  incipient  fires  in  the  freight. 

Miscellaneous  Equipment.  —  Piers  should  be  equipped 
with  fire  buckets  and  in  cold  climates  with  tanks  of  water 
to  which  enough  salt  has  been  added  to  prevent  freezing. 
Such  tanks,  containing  both  salt  water  and  a  number  of 


EQUIPMENT  OF   WHARVES  AND  PIERS        199 

buckets,  are  sold  by  the  dealers  in  fire-extinguishing  supplies 
and  are  most  suitable  for  the  conditions  existing  on  piers. 
Hydrants  and  hose  should  also  be  installed  and  should  be 
arranged  so  that  they  will  not  be  obstructed  by  freight  piled 
in  front  of  them. 

Watchmen's  clocks  should  be  included  in  the  fire  pro- 
tective apparatus  in  order  to  ensure  the  efficient  patrol  by 
the  men  employed  for  the  purpose. 


CHAPTER  VIII 
CARGO-HANDLING  MACHINERY 

GENERAL  CONSIDERATIONS 

THIS  chapter  treats  of  machinery  for  handling  package 
freight  and  does  not  cover  apparatus  for  bulk  cargoes,  such 
as  coal,  ore,  grain,  and  oil,  for  which  special  machinery  is 
required  for  each  kind  of  material. 

Object.  —  The  object  to  be  attained  by  the  installation 
of  freight-handling  machinery  on  wharves  is  the  reduction 
of  the  cost  of  transportation  by  saving  in  the  cost  of  labor, 
by  increasing  the  speed  of  loading  and  unloading  vessels, 
and  by  reducing  the  cost  of  high  tiering  of  freight  on  the 
wharf.  The  increase  of  speed  increases  the  efficiency  of 
the  vessels  by  increasing  the  tonnage  carried  by  ships  in  a 
given  time,  and  economical  high  tiering  reduces  the  area  of 
wharf  necessary  to  handle  the  required  amount  of  freight. 

Function.  -  -  The  function  of  cargo-handling  machinery 
for  wharves  is  the  transfer  of  freight  between  the  wharf 
and  the  vessel  and  its  transportation  on  the  wharf.  The 
commonest  method  is  by  use  of  the  ship's  hoisting  gear  and 
two- wheeled  or  four-wheeled  longshoreman's  hand-trucks. 
This  method  may  be  made  very'  rapid,  but  it  is  very  ex- 
pensive, the  principal  factors  being  the  large  amount  of 
highly  paid  labor  and  the  large  area  of  wharf  required. 
Up  to  within  a  few  years  ago  little  progress  had  been  made 
in  reducing  the  cost  of  cargo  handling  by  the  introduction 
of  improved  machinery  and  appliances.  Some  explanation 
of  this  may  be  found,  as  in  the  case  of  fire  protection,  in 
the  number  of  parties  involved  in  the  various  operations. 
For  example,  one  company  may  own  the  wharf  and  shed 
and  lease  them  to  a  steamship  company  which  makes  a 


CARGO-HANDLING  MACHINERY  201 

contract  with  a  stevedore,  at  so  much  a  ton  .for  unloading 
the  freight,  which  he  deposits  on  the  pier  for  the  consignee's 
truckman  to  take  away.  It  is  difficult  under  such  condi- 
tions to  obtain  cooperation  among  those  interested  and  to 
introduce  new  methods  and  machinery  involving  large 
outlays  of  capital,  the  abolition  of  long-established  customs 
and  emoluments,  and  the  overcoming  of  the  objections  to 
the  introduction  of  labor-saving  devices.  In  a  very  few 
instances,  however,  all  the  operations  involved  in  the 
transfer  of  freight  between  vessel  and  consignee  are  con- 
trolled by  one  party,  and  where  such  conditions  occur,  may 
be  found  progressive  policies  and  methods,  and  the  success- 
ful use  of  machinery  with  reduction  in  cost  and  increase  of 
efficiency  of  vessels  and  wharves. 

Another  reason  why  improved  machinery  has  been  intro- 
duced to  such  a  small  extent  may  be  found  in  the  fact  that 
the  advantage  of  any  machinery  involving  high  fixed 
charges  depends  largely  on  the  "load  factor,"  or  ratio  of 
employed  to  idle  time.  Where  freight  handling  is  con- 
ducted night  and  day  the  opportunity  for  economies  by  its 
employment  is  much  greater  than  where  such  an  equipment 
is  only  in  use  say  one  fifth  of  the  time,  as  is  often  the  case. 

Operations  to  be  Performed.  —  The  operations  to  be 
performed  in  cargo  handling  may  be  divided  into  three 
classes : 

1.  Hoisting  and  lowering   on  the   steamer,   lighter,   or 
other  vessel. 

2.  Transfer   between   the   vessel   and   the   wharf   shed, 
warehouse,  car,  dray,  or  another  vessel. 

3.  Transfer  between  the  shed  and  the  warehouse,  car,  or 
dray. 

Incidental  to  the  transfer  are  sorting,  weighing,  gauging 
and  measuring,  marking,  customs  examining,  sampling, 
recoopering,  and  checking. 

On  outbound  freight,  in  order  to  keep  the  idle  time  of 
the  vessel  at  a  minimum,  the  sorting  is  usually  limited  to 


202  WHARVES  AND  PIERS 

putting  the  freight  for  each  port  of  delivery  together  and 
stowing  it  with  reference  to  its  weight,  bulk,  and  perisha- 
bility. When  the  vessel  has  only  one  port  of  call  a  large 
part  of  this  sorting  is  eliminated. 

The  result  of  this  kind  of  loading  is  that  when  the  cargo 
is  unloaded  it  comes  out  of  the  ship  with  the  consignments 
all  mixed  together.  The  sorting  is  usually  done  on  the 
wharf,  in  order  to  save  the  vessel's  time,  and,  with  the 
other  incidental  operations,  forms  the  greatest  obstacle  to 
the  economical  use  of  machinery  on  the  wharf.  The 
average  consignment  may  vary  from  half  a  ton  to  one  or 
more  car  loads,  and  the  cost  of  handling  and  the  possibilities 
for  saving  by  the  use  of  machinery  depend  to  a  considerable 
extent  on  this  average  size.  In  the  sorting  of  small  consign- 
ments the  two-wheeled  hand  truck  has  the  greatest  ad- 
vantage and  motor  trucks,  telphers,  or  other  carriers  of 
large  capacity  are  inefficient. 

It  is  obviously  impossible  to  formulate  any  general  plan 
in  regard  to  cargo  handling  and  the  object  of  this  chapter 
is  to  describe  various  conditions  which,  in  various  com- 
binations, may  have  to  be  provided  for,  and  the  methods 
and  machinery  in  use. 

Classification  of  Vessels. --Vessels  may  be  divided,  for 
consideration  in  connection  with  cargo-handling  machinery, 
into  those  in  which  the  cargo  is  hoisted  on  and  off  and 
those  in  which  the  cargo  is  trucked  on  and  off.  Trans- 
oceanic freight  ships  usually  load  their  cargo  through 
comparatively  small  hatches  in  the  deck.  Many  coastwise 
vessels  which  carry  both  passengers  and  freight  have 
extensive  deck  houses,  few  deck  hatches  or  none  at  all, 
and  load  partly  or  wholly  through  side-ports,  by  means  of 
trucks.  On  side-port  vessels  having  more  than  one  cargo 
deck,  the  cargo  is  hoisted  from  the  lower  decks  to  the  deck 
on  which  the  trucks  enter  by  means  of  elevators  or  cranes 
installed  on  the  ship.  Bay,  sound,  and  river  steamboats 
usually  are  in  the  second  of  the  above  classes.  Canal  boats 
are  in  the  first  class  but  do  not  carry  hoisting  gear.  Derrick 


CARGO-HANDLING  MACHINERY 


203 


lighters  are  in  the  first  class  and  covered  lighters  in  the 
second. 

Heavy  Packages.  —  Packages  weighing  over  five  tons 
cannot  usually  be  handled  by  the 
ship's  gear.  Floating  cranes  and 
derricks  are  used  in  most  ports  for 
this  purpose,  as  it  is  not  economical 
to  equip  the  wharves  with  machinery 
capable  of  handling  occasional  loads 
of  such  weight. 

CLASSIFICATION  AND  DESCRIPTION  OF 
MACHINERY  AND  APPLIANCES 

Machinery  for  freight  handling 
may  be  classified  into  that  used  for 
hoisting  and  transporting.  The  ap- 
pliances for  hoisting  are  cargo 
booms,  winches,  hatch-cranes  and 
elevators,  on  the  vessels,  and  cranes  of  various  patterns, 
telphers,  cargo  masts  and  portable  winches  on  the  wharves. 


Fig.  130.     Two-wheel 
Freight  Truck. 


Fig.  131.     Four-wheel  Freight  Truck. 

For  transferring  freight  between  vessels  and  wharf  shed 
there  are,  in  addition  to  all  the  above,  except  the  ships' 
cranes  and  elevators,  two  and  four-wheeled  hand  trucks, 


204 


WHARVES  AND  PIERS 


motor  trucks,  and  portable  conveyors,  and  for  transporting 
freight  on  the  wharf  there  are,  in  addition  to  these,  flat- 
boards  or  low  four-wheeled  trucks  drawn  by  horses  or 
mules,  motor  trucks  with  trailers,  and  overhead  travelling 
cranes. 

Other  appliances  are  portable  electric  controllers,  inclined 
truck  elevators,  slides  between  wharf  and  vessel,  and  chutes 

and  other  devices  for  use  be- 
tween the  floors  of  double 
deck  sheds. 

Ships'  Gear.  —  Freight 
ships  for  trans-oceanic  trade 
are  usually  equipped  with 
masts  and  from  two  to 
seven  cargo  booms  and 
winches  to  each  hatch. 

Fig.  133  shows  a  recently 
built  type  of  freight  steamer 
with  a  very  elaborate  equip- 
ment of  cargo  gear  which 
permits  of  handling  cargo 
from  each  of  the  two  largest 
hatches  on  both  sides  of  the 
ship  at  the  same  time.  One 
cargo  boom  on  each  mast 
is  designed  to  handle  extra 
heavy  loads.  Fig.  134  illus- 
trates a  steamer  with  the  or- 


Fig. 132.     Loading  Ship  with 
Inclined  Skid. 


dinary  equipment  of  cargo  booms.  The  winches  are  placed 
on  raised  platforms  to  permit  the  operators  to  see  into  the 
hold.  This  platform  is  only  found  on  the  newer  ships. 
Fig.  135  shows  a  lumber  schooner  with  very  high  booms 
and  elevated  platforms  for  the  winches.  The  usual  method 
of  unloading  with  this  equipment  is  to  rig  the  booms  of 
each  pair  at  about  45°  with  the  keel,  hoist  the  load  with 
both  lines,  and  lower  it  with  one.  In  loading  the  opera- 
tion is  reversed.  With  this  arrangement  the  cargo  can  be 


CARGO-HANDLING  MACHINERY 


205 


H 

hi    | 
SI    I 


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t 


q  i 

:l    S 


206  WHARVES  AND  PIERS 

handled  on  either  side  of  the  vessel  without  shifting  the 
booms.  The  winches  are  arranged  so  that  one  man  handles 
both  lines  and  the  extended  operating  platforms  permit  of 
a  good  view  into  the  hold. 

The  type  of  winch  in  which  the  rope  is  not  wound 
on  a  drum  but  on  an  extension  winch  head,  thus  re- 
quiring an  operator  for  each  line,  is  much  in  use  and 
is  apparently  wasteful  of  labor.  Double  and  triple 
drum,  steam-driven  winches,  which  wind  the  rope  on 
the  drums,  are  rapidly  and  safely  operated  by  one  man 
in  handling  derricks  on  land,  and  there  is  no  obvious 
reason  why  similar  machines  should  not  be  used  on 
ships  and  wharves.  Winches  of  this  nature  have  re- 
cently been  placed  on  the  market  and  are  shown  in  the 
illustrations. 

Hatch  cranes  and  elevators  for  vessels  which  load 
through  side  ports  are  shown  in  Fig.  138. 

Wharf  Machinery.  —  Wharf  machinery  is  operated  by 
steam,  hydraulic,  or  electrical  power,  but  the  latter  is 
almost  universally  used  in  new  installations. 

Cranes.  —  Of  wharf  cranes  there  are  several  patterns. 
The  revolving  crane  is  the  most  common.  This  consists 
of  a  derrick  with  a  boom  or  jib  which  may  be  raised  or 
lowered  by  an  independent  motor  mounted  on  a  turn-table 
which  is  carried  by  some  sort  of  a  car  moving  on  tracks. 
The  car  may  be  of  the  ordinary  low  railroad  type  or  may  be 
of  the  " portal  crane"  or  " gantry"  type  in  the  form  of  a 
movable  bridge,  spanning  a  roadway  or  one  or  more  railroad 
tracks  on  the  side  of  the  wharf  or  pier.  One  of  the  rails 
may  be  placed  on  the  side  of  a  shed,  in  which  case  the  machine 
is  called  a  "semi  portal  crane."  Such  machines  are  usually 
built  with  little  regard  to  the  load  on  the  track  and  are 
very  heavy  on  account  of  the  counterweights  which  are 
employed  to  balance  the  boom  and  the  moving  load.  This 
is  of  considerable  disadvantage  on  pile  foundations,  and 
some  recent  machines  have  been  designed  in  which  the 
weight  has  been  reduced  as  much  as  possible.  Revolving 


CARGO-HANDLING  MACHINERY 


207 


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I 

I 
n 

o 

J= 


E'  H     -a 


208 


WHARVES  AND  PIERS 


CARGO-HANDLING  MACHINERY 


209 


cranes  are  also  mounted  on  cars  which  run  on  the  roofs  of 
freight  sheds. 

Roof  cranes  may  also  be  of  the  " straight  line"  type  with 


Fig.  136.     Ordinary  Type  of  Ship's  Winch:     Two  Lines 
Operated  by  Two  Men. 


Fig.  137.     Winch  for  Two  Lines  operated  by  One  Man. 

a  vertically  hinged  arm  carrying  a  trolley.  Another  pattern 
has  the  trolley  arm  suspended  on  trunnions  in  such  a  way 
that  when  it  is  in  position  for  operating,  it  extends  both  over 


210 


WHARVES  AND  PIERS 


the  vessel  and  inside  the  door  of  a  shed  so  that  the  loads 
can  be  landed  inside  the  latter. 

Telphers.  -  -  Telphers  are  electric  cars  running  above  the 


Fig.  138.     Hatch  Cranes  and  Elevator  for  Ships  with  Side  Ports. 


Fig.  139.     Electric  Locomotive  Crane. 

deck  of  a  wharf  at  a  height  sufficient  to  clear  the  cargo, 
on  single  rails  suspended  from  frames,  either  those  of  a 
freight  shed  or,  in  the  case  of  an  unshedded  wharf,  those 


CARGO-HANDLING  MACHINERY 


211 


erected  specially  for  the  purpose.  The  car  carries  its 
motors,  the  operator,  and  electrically  operated  hoists  for 
raising  and  lowering  the  loads.  Each  motor  car  may  also 
be  provided  with  a  number  of  trailers  similarly  equipped 
with  hoisting  gear.  The  loads  are  carried  in  crates  or  on 
"flat  boards"  suspended  from  the  motor  car  or  trailers. 

If  the  tracks  are  fitted  with  fixed  switches  they  require 
many  parallel  lines  of  rails  to  cover  a  given  area.  A  device 
called  a  gliding  switch  has 
been  used  considerably  in 
Europe,  and  to  a  small  ex- 
tent in  this  country,  which 
permits  a  rail  on  a  travel- 
ling bridge  or  shop  crane  to 
be  connected  with  another 
rail  at  right  angles  to  it 
wherever  the  travelling 
crane  may  be,  as  shown  in 
Fig.  145.  This  device  allows 
such  a  travelling  crane  to 
be  substituted  for  the  nu- 
merous parallel  cross  rails 


Fig.  140.     Gantry  or  Portal  Crane. 


necessary  in  the  system  using  fixed  switches.  The  combin- 
ation of  a  travelling  bridge  crane  fitted  with  rails'  and 
gliding  switches  permits  the  telpher  to  serve  the  entire  area 
served  by  the  travelling  bridge. 

New  York  Cargo  Hoists.  —  Cargo  hoists,  such  as  are 
shown  in  Figs.  96,  112,  116  and  118,  have  been  developed 
in  New  York  for  transferring  cargo  between  the  wharf  and 
steamships  equipped  with  cargo  booms  and  winches.  For 
want  of  a  better  name  they  may  be  called  the  New  York 
Cargo  hoist.  They  consist  of  upright  steel  or  wooden 
columns  at  the  side  of  the  pier  shed  which  support  wire 
cables  or  steel  girders  to  which  cargo-hoisting  pulleys  or 
blocks  may  be  attached.  The  function  performed  by  these 
hoists  may  be  performed  by  an  extra  cargo  boom  on  the 
ship,  but  they  have  the  advantage  of  supplying  a  point  of 


212 


WHARVES  AND  PIERS 


suspension  for  the  block  at  the  best  location,  which  cannot 
always  be  supplied  by  the  ship's  boom,  especially  when  the 


Fig.  141.     Semi-portal  Crane. 

ship  is  moored  at  some  distance  from  the  wharf  to  allow 
coal  lighters  to  lie  between  the  ship  and  the  wharf. 


Fig.  142.     Straight  Line  Crane  on  Roof  of  Wharf  Shed,  Rotterdam. 

Portable  electric  winches  are  used  on  the  wharves  to 
operate  whips  or  single  hoisting  lines  rove  through  the 
blocks  on  the  cables  or  girders  between  the  cargo  masts. 


CARGO-HANDLING  MACHINERY 


213 


Motor  Trucks.  —  Electric  freight  trucks  operated  by  stor- 
age batteries  have  been  placed  on  the  market  in  recent  years 
to  take  the  place  of  hand-operated  trucks.  They  have  a 
capacity  of  about  two  tons  and  a  speed  of  five  to  seven 
miles  an  hour.  Some  of  them  are  arranged  to  run  under  a 
skid  or  platform  with  short  legs,  raise  it  a  few  inches,  and 


Fig.  143.     Straight  Line  Crane  delivering  Freight  inside  Wharf  Shed. 

transport  it  with  its  load  of  freight.  If  these  skids,  which 
are  inexpensive,  are  supplied  in  excess  of  the  number  of 
motor  trucks,  the  efficiency  of  the  motor  truck  is  increased 
by  reducing  the  time  spent  in  loading  and  unloading  it. 
Some  motor  trucks  are  fitted  with  cranes  and  some  are 
designed  to  act  as  locomotives  and  haul  a  number  of  trailers. 
Conveyors.  —  Portable,  electrically  operated  conveyors, 
such  as  are  illustrated  in  Fig.  150,  are  used  for  transferring 
freight  in  uniform  packages,  such  as  sugar,  coffee,  cement, 
canned  goods,  etc.,  from  the  vessel's  hatch  to  the  wharf. 


214 


WHARVES  AND  PIERS 


They  are  made  in  sections  which  can  be  easily  moved  about. 
A  slightly  different  form  is  used  at  the  end  of  a  line  for 
tiering. 

Portable  Controllers.  —  Portable  electric  controllers  have 
been  used  for  some  years  in  Europe  and  have  recently  been 


Fig.  144.     Telpher  Train. 

put  on  the  market  by  one  of  the  large  electric  manufacturing 
companies  in  this  country.  They  are  carried  on  a  belt 
worn  by  the  operator  and  are  connected  to  the  motors  of  a 
hoisting  winch  or  crane  by  flexible  electric  conductors. 
By  use  of  this  device  the  operator  of  a  hoisting  machine 
can  stand  at  the  edge  of  a  ship's  hatch  and  see  the  load  he 
is  hoisting  at  all  stages  of  the  operation,  thus  increasing  the 
speed  and  dispensing  with  the  services  of  signalmen.  As 
they  are  made  to  control  two  motors,  one  man  can  operate 
a  double-drum  winch  or  two  machines,  such  as  a  ship's 
winch  and  a  dock  winch. 


CARGO-HANDLING  MACHINERY  215 

Inclined  Truck  Elevators.  —  Inclined  truck  elevators  con- 
sist of  electrically  driven  chains  running  in  a  slot  in  a  wharf- 
drop  or  inclined  ramp.  The  chains  are  fitted  with  lugs  or 
hooks  which  engage  the  axles  of  hand  or  motor  trucks  and 
carry  them  up  the  grades  on  which  they  require  assistance. 

LOADING  AND  UNLOADING  SHIPS 

Cranes  vs.  Ship's  Gear. --The  two  principal  appliances 
in  use  for  hoisting  freight  to  and  from  vessels  not  equipped 
with  side  ports  are  the  ship's  cargo  gear  and  wharf  cranes. 
In  Europe  the  wharf  crane  is  the  most  common  and  in  this 

A  c'  .  c  B 


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ii 

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Moveable  Bridge 
D               or 
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S^>            •  —  >          Y 

Fig.  145.     Travelling  Bridge  with  Gliding  Switches. 

country  the  ship's  tackle  is  almost  universal.  When  the 
ship's  tackle  is  used  one  hoisting  block  is  suspended  from  the 
end  of  a  cargo  boom  over  the  hatch  and  another  from 
another  boom  or  from  the  cable  or  girder  between  the 
cargo  masts  on  the  wharf,  over  the  point  on  the  wharf 
where  the  load  is  to  be  deposited.  Two  lines  are  attached 
to  the  sling  which  carries  the  load,  each  leading  to  a  drum 
of  a  hoisting  winch.  The  load  is  first  raised  by  one  line, 
then  transferred  to  and  lowered  by  the  other  line. 

Where  wharf  cranes  are  installed,  they  are  usually  used 
to  hoist  the  freight  from  the  hold  of  the  vessel  but  sometimes 
the  cargo  is  hoisted  to  the  deck  by  the  ship's  winches  and 
transferred  to  the  wharf  by  the  crane. 

The  comparative  advantages  of  the  two  methods  may  be 
summed  up  as  follows:  The  revolving  crane  wastes  time 
in  its  rotary  motion  and  the  length  of  the  path  described 
by  the  load,  also  in  stopping  the  hook  or  load  at  the  proper 


216 


WHARVES  AND  PIERS 


point.  The  crane  is  limited  in  its  action  by  the  shrouds  on 
the  ship's  masts.  The  modern  ship's  gear  is  said  to  be  as 
rapid  on  package  freight  as  the  revolving  crane,  even 
though  the  latter  may  lift  a  larger  load.  The  crane  requires 


Fig.  146.     Telpher  System  with  Gliding  Switches  for  a  Freight  Pier. 

a  larger  outlay  of  capital  than  the  New  York  cargo  hoist 
and  dock  winch,  and  may  be  in  use  only  a  small  portion  of 
the  time.  It  is  often  heavy  and  increases  the  cost  of  founda- 
tions in  pile  structures.  It  requires  only  one  operator,  while 
the  two-line  method  usually  requires  two  or  more.  This 
disadvantage  may  be  overcome,  however,  by  means  of  the 
portable  electric  controller  described  above.  The  crane 
is  a  necessity  where  cargo  is  to  be  transferred  to  and  from 
barges  and  other  vessels  which  have  no  cargo  gear. 

The   modern    crane   and   the   modern   portable   electric 
dock  winch  combined  with  the  New  York  cargo  hoist  are 


CARGO-HANDLING  MACHINERY 


217 


both  much  superior  in  speed,  and  require  fewer  men  to 
operate,  than  the  ships'  winches  in  ordinary  use.  For  this 
reason  they  should,  where  there  is  sufficient  traffic,  be 
placed  on  wharves  and  piers  except  in  cases  where  the 
ships  using  the  wharves  are  equipped  with  an  ample  number 
of  cargo  booms  and  winches  of  the  most  economical  type. 


=13 

'TiTttf 


Fig.  147.    New  York  Cargo  Hoists,  showing  Use  of  Winches  on  the 
Ship  and  on  the  Pier. 

The  New  York  cargo  hoist  is  more  economical  than  the 
crane,  is  fully  as  rapid,  and  is  therefore  superior  wherever 
it  fulfils  all  the  conditions.  The  crane  serves  a  larger  area 
than  the  ship's  tackle  and  can,  therefore,  prevent  congestion 
on  the  wharf  due  to  delays  in  clearing  the  point  where  the 
freight  is  landed. 

The  straight-line  crane  does  not  serve  so  large  an  area 
as  those  of  the  revolving  type,  but  its  load  does  not  have  to 
follow  as  long  a  path. 

In  loading  vessels  the  loads  are  often  dragged  up  an 
inclined  skid  or  slide  between  the  wharf  and  the  ship,  thus 


218  WHARVES  AND  PIERS 

avoiding  the  use  of  two  hoisting  lines  and  the  accompanying 
labor. 

It  is  somewhat  difficult  to  understand  why  the  use  of 
cranes  is  so  prevalent  abroad  and  so  exceptional  in  this 
country,  and  why,  when  a  steamship  company  with  almost 
unlimited  capital,  a  few  years  ago,  rebuilt  its  piers  which 
had  been  burned,  it  equipped  them  with  the  New  York 
pattern  of  cargo  hoists  when  the  piers  of  the  same  company 


Fig.  148.     Electric  Motor  Truck. 

in  Germany  are  equipped  with  over  one  hundred  revolving 
cranes.  Many  reasons  have  been  suggested.  One  of  them 
is  that  the  crews  are  discharged  and  fires  drawn  in  home 
ports  in  Europe,  but  retained  here,  and  that  boilers,  winches, 
and  crew  are  available  here  to  work  cargo.  On  the  other 
hand,  it  is  stated  that  one  line  of  steamships  handles  cargo 
in  its  home  port  in  Europe  with  the  ship's  gear,  though  the 
wharf  is  supplied  with  cranes ;  moreover,  most  ships  are  fitted 
with  donkey  boilers  for  operating  winches,  etc.,  when  the 
main  boilers  are  out  of  use.  Besides  this,  the  dock  winch 
with  the  portable  controller  would  be  sufficient  even  if  there 
were  no  power  available  in  the  ships.  Another  reason  given 
is  that  the  tidal  range  in  some  European  ports  is  so  great 


CARGO-HANDLING  MACHINERY 


219 


that  ship's  tackle  cannot  be  used  to  advantage  when  the  tide 
is  low.     The  New  York  cargo  hoist  would  solve  this  problem 


Fig.  149.     Motor  Truck  with  Separate  Cargo  Platform. 

as  well  as  the  crane.  Another  possible  explanation  is  that 
the  cranes  are  supplied  by  the  municipalities  which  own 
the  docks,  and  that  the  steamship  companies  would  not  in 


Fig.  150.     Sectional  Portable  Conveyor. 

many  cases  install  them  at  their  own  expense.  Probably 
the  best  reason  is  that  at  nearly  all  European  ports  there 
are  a  great  many  deep-hulled  barges  and  similar  vessels 


220 


WHARVES   AND   PIERS 


which  have  no  cargo  gear  at  all  and  that  many  steamships 
are  more  or  less  deficient  in  their  equipment  of  booms  and 
winches,  and  that  the  revolving  crane  has  a  greater  range 
of  usefulness  than  any  other  form  of  cargo-handling  ma- 


Fig.  151.     Portable  Electric  Controller  for  operating 
Winches  on  Wharves  or  on  Ships. 

chinery.  In  New  York,  practically  the  only  vessels  which 
have  no  cargo  gear  which  come  to  steamship  piers  are  those 
which  unload  their  freight  by  means  of  trucks  from  deck 
to  wharf,  and  coal  barges  for  coaling  ships.  The  coal  is 
hoisted  by  means  of  light  temporary  booms,  ship  or  dock 
winches,  or  winches  on  small  scows  which  accompany  the 
coal  barges.  When  the  New  York  State  Barge  Canal  is 


CARGO-HANDLING   MACHINERY  221 

completed  it  is  expected  that  the  vessels  which  will  be  used 
on  it  will  be  of  over  2000  tons'  capacity  and  that  they  will 
carry  their  cargoes  in  hulls  about  12  feet  deep  and  that 
they  will  have  no  cargo  gear.  It  is  probable  that  the 
wharves  constructed  by  the  State  at  the  terminals  on  this 
canal  will  be  equipped  with  cranes  for  cargo  handling. 

Neither  the  New  York  cargo  hoist  nor  the  crane  will 
transfer  freight  between  a  steamer  at  a  wharf  and  a  barge 
or  lighter  lying  on  the  opposite  side  of  the  vessel.  The 
ships'  tackle  may  perform  this  work  if  the  hatch  is  large 


Fig.  152.     Portable  Electric  Winch  with  Two  Independent  Drums 
and  Portable  Controller. 

enough  while  a  wharf  crane  is  working  on  the  opposite  side 
of  the  steamer.  If  a  steamer  is  equipped  with  only  two 
cargo  booms  to  a  hatch  the  New  York  dock  cargo  hoist 
could  not  be  used  while  freight  is  being  transferred  between 
ships  and  lighters  unless  a  temporary  boom  were  rigged  up. 
Speed-limiting  Points. --The  limiting  point  of  speed  in 
loading  and  unloading  is  usually  on  the  vessel.  The  rate 
at  which  cargo  can  be  handled  is  not  limited  ordinarily 
by  the  speed  at  which  the  hoisting  apparatus  can  be  operated 
but  by  the  rapidity  with  which  the  cargo  can  be  stowed  in 
the  hold  or  broken  out  and  made  up  into  loads  for  hoisting. 
With  some  kinds  of  cargo,  when  ships'  gear  and  hand 


222 


WHARVES   AND   PIERS 


trucks  are  used,  the  limiting  point  in  unloading  may  be 
the  landing  point  on  the  wharf,  but  such  a  condition  is 
unusual. 

Reservoirs.  —  As  the  operations  in  the  vessel  as  well  as 
those  on  the  wharf  are  both  subject  to  interruption  and 
irregularities  and  in  order  that  one  may  not  delay  the 
other  and  cause  men  and  machinery  to  stand  idle,  a  reservoir 
or  place  of  deposit  must  be  provided  between  the  two 


Fig.  153.     Inclined  Truck  Elevator. 

operations  where  the  freight  may  accumulate  and  diminish. 
It  is  essential  that  there  should  be  ample  deck  space  at  the 
point  where  freight  is  landed  on  the  wharf  by  cranes  or 
ships'  gear  to  supply  such  a  reservoir,  and  that,  in  order  to 
avoid  extra  handling  in  the  reservoir,  an  adequate  supply 
of  extra  carriers  should  be  provided  except  where  the  two- 
wheeled  truck  is  the  only  means  of  conveyance.  An  ex- 
ample illustrating  the  above  is  found  in  unloading  coffee 
in  bags.  The  latter  were  hoisted  by  the  ships'  gear  and 
deposited  on  four-wheeled  platform  trucks.  Only  enough 
trucks  were  provided  to  equal  the  capacity  of  the  hoisting 


CARGO-HANDLING   MACHINERY  223 

apparatus.  In  spite  of  all  efforts  the  trucks  became  grouped 
and  there  were  times  when  it  was  necessary  to  stop  the 
hoisting  and  with  it  the  work  of  a  large  gang  of  men  in 
the  hold  of  the  vessel,  or  deposit  the  bags  on  the  deck  of  the 
wharf,  to  be  subsequently  loaded  on  to  the  trucks  by  addi- 
tional labor.  A  reservoir  consisting  of  an  inclined  slide 
with  a  capacity  of  two  or  three  truck  loads  obviated  the 
difficulty  and  made  the  hoisting  apparatus  the  limiting 
element  of  speed.  A  similar  condition  may  occur  at  the 
end  of  a  line  of  conveyors. 

FREIGHT  HANDLING  ON  THE  WHARF 

The  cost  of  freight  handling  may  be  divided  into  that 
incurred  on  the  vessel  in  stowing  and  breaking  down  cargo, 
the  transfer  between  yessel  and  wharf,  and  the  handling 
on  the  wharf.  The  average  cost  of  unloading  steamships 
has  been  estimated  as  follows: 

Hoisting  and  lowering  with  cranes $0. 02  to  0. 05 

"        with  two  winches ...  $0. 04  to  0. 10 

Distributing  and  tiering $0. 29  to  0. 36 

Loading  on  drays $0. 20 

Sorting  before  hoisting  doubles  the  cost  of  hoisting  and 
lowering.  As  there  are  almost  no  mechanical  devices  for 
reducing  the  cost  of  the  work  in  the  vessels'  holds,  and  as 
the  cost  of  transfer  between  vessel  and  wharf  is  only  about 
one  fifth  of  the  cost  of  handling  the  freight  on  the  wharf, 
the  latter  becomes  the  main  point  for  attack  in  reducing 
the  cost. 

The  principal  appliances  which  today  are  available  for 
this  purpose,  in  place  of  the  ordinary  hand  trucks,  are 
storage-battery  trucks  and  telphers.  Other  appliances  to 
be  considered  are  horse-drawn  trucks,  conveyors,  and 
stackers. 

Hand  Trucks.  -  -  The  two-wheeled  longshoreman's  truck 
transports  a  large  load  for  one-man  power,  it  is  very  flexible, 
allows  of  rapid  sorting  of  small  consignments,  can  be  operated 
in  narrow  roadways,  and  has  very  low  fixed  charges  for 


224  WHARVES,   AND   PIERS 

interest  repairs,  depreciation,  and  insurance.  It  can  be 
made  rapid  in  operation,  but  it  is  high  in  labor  cost.  It 
can  perform  any  of  the  functions  of  the  other  machines 
mentioned  above  except  tier  and  load  drays  or  railroad  cars. 
It  requires  no  expensive  overhead  structure  or  extra  founda- 
tions, but  it  does  require  a  smooth  surface  to  operate  on. 

Electric  Trucks.  -  -  The  electric  truck  carries  a  larger 
load  than  a  hand  truck,  moves  faster,  and  requires  less 
labor,  but  has  a  very  high  first  cost,  high  charges  for  interest 
and  insurance,  a  high  maintenance  cost,  and  should  be 
charged  with  a  high  rate  of  obsolescence.  It  can  go  up 
grades  without  extra  cost  for  labor,  and,  by  means  of 
portable  ramps,  it  can  enter  box  cars  standing  on  the  deck 
of  the  wharf.  Equipped  with  a  crane,  it  can  load  drays 
and  cars,  transport  heavy  packages,  and  tier  to  a  limited 
extent.  It  will  work  at  a  speed  which  is  uneconomical 
for  hand  trucks  and  thus  increase  the  efficiency  of  ship  and 
wharf.  As  it  carries  a  larger  load  than  the  hand  truck,  it  is 
not  as  flexible  in  sorting  and  distributing  small  consign- 
ments. When  it  is  used  in  combination  with  a  tiering 
machine,  cargo  can  be  tiered  up  to  whatever  height  is  re- 
quired. Like  the  hand  truck  it  does  not  require  any  special 
construction  in  the  wharf  shed. 

Telphers.  -  -  The  great  advantage  of  a  telpher  system  is 
that  it-  serves  every  cubic  foot  of  space  in  a  shed,  thus  in- 
creasing the  storage  capacity  by  high,  tiering.  It  also 
decreases  the  amount  of  deck  space  required  for  passage- 
ways for  trucks  which  operate  on  the  deck.  It  can  load  and 
unload  heavy  packages  from  drays  and  cars.  It  .can,  by 
means  of  travelling  loops  extending  over  the  decks  of  vessels, 
hoist  directly  in  and  out  of  the  ships  and  can  transport 
goods  directly  from  a  vessel  to  a  warehouse  on  shore.  It 
has  a  special  advantage  where  it  is  possible  to  transfer 
freight  directly  between  car  and  vessel.  It  does  not  require 
depressed  tracks  nor  does  it  require  frequent  shifting  of  cars, 
as  it  costs  little  more,  within  reasonable  limits,  to  transport 
a  load  a  long  distance  horizontally  at  high  speed  than  a 


CARGO-HANDLING   MACHINERY  225 

short  one.  In  fact,  it  is  a  universal  tool  which  can  perform 
all  the  operations  of  freight  handling  on  a  wharf.  It  has  the 
disadvantage,  however,  of  requiring  a  building  of  special 
height,  extra  strength  in  the  posts  or  columns,  extra  founda- 
tions, and,  on  wide  piers,  extra  long  spans  in  the  roof, 
together  with  the  necessary  girders,  tracks,  switches  and 
movable  bridges,  which  entail  large  outlays  of  capital 
and  increase  of  fixed  charges.  The  rolling  stock  is  some- 
what cheaper  than  an  equivalent  number  of  motor  trucks, 
as  no  storage  batteries  are  required.  The  telpher  system 
cannot  be  applied  to  sheds  of  ordinary  height  without 
sacrificing  the  high  tiering  which  is  one  of  its  chief  ad- 
vantages. 

In  a  design  for  a  pier  1100  feet  long  and  150  feet  wide,  to 
be  equipped  with  a  telpher  system,  the  estimated  increase 
in  the  cost  of  the  pier  and  shed  due  to  extra  height  and 
weight  of  shed,  a  roof  with  three  rows  of  posts  instead  of 
four,  heavier  foundations,  etc.,  was  about  5  or  6%  and  the 
cost  of  the  equipment,  which  included  overhead  tracks, 
electrical  equipment,  6  travelling  bridges  with  gliding 
switches,  16  main  track  switches,  and  4  trains,  each  con- 
sisting of  one  tractor  and  3  carriers,  was  estimated  at  over 
$50,000. 

Such  a  large  initial  outlay  of  capital  is  a  great  obstacle 
to  the  introduction  of  this  system,  especially  where  the 
amount  of  traffic  cannot  be  definitely  estimated.  While  this 
system  is  ideal  from  a  mechanical  standpoint,  it  has  not 
had  enough  applications  to  prove  whether  it  can  be  made 
more  economical  than  hand  or  motor  trucks. 

Horse  Trucks.  —  For  long-distance  transportation,  such 
as  that  between  a  pier  shed  and  a  warehouse  on  shore 
averaging  from  1000  to  1500  feet,  the  motor  truck  has  to 
compete  with  trucks  hauled  by  horses  or  mules.  These 
are  arranged  so  that  the  horse  is  easily  shifted  from  one 
truck  to  another,  so  that  the  horse  and  driver  do  not  stand 
idle  during  the  unloading  of  the  trucks.  These  are  more 
economical  than  hand  trucks  for  this  purpose  and  are 


226  WHARVES  AND   PIERS 

governed  by  about  the  same  conditions.  Motor  trucks  for 
this  purpose  may  carry  the  load  or  may  be  arranged  as 
tractors  to  pull  a  separate  truck.  It  is  improbable  that  at 
present  prices  they  can  show  superior  economy  to  the 
horse  as  a  tractor  except  for  longer  distances  than  those 
mentioned  above,  where  their  speed  will  have  a  large  in- 
fluence. A  motor  truck  carrying  a  crate  or  flat  board, 
which  can  be  filled  in  the  vessel,  picked  up  by  the  motor 
truck  from  the  deck  of  the  pier  and  left  at  the  warehouse 
to  be  unloaded  while  the  truck  is  making  another  trip, 


Fig.  154.     Horse  Truck  for  use  between  Piers  and  Warehouses, 
Brooklyn,  N.  Y. 

would  probably  show  the  best  results.  Some  such  scheme 
could,  however,  also  be  applied  to  the  horse-drawn  truck, 
and  it  is  doubtful  if  the  superior  speed  of  the  motor  truck 
for  this  service  can  compensate  for  the  high  fixed  charges, 
except  where  they  can  be  operated  with  a  much  higher  load 
factor  than  is  usual. 

Direct  Transfer  between  Cars  and  Ships.  —  A  very 
considerable  saving  in  the  cost  of  handling  freight  could 
be  made  if  it  were  possible  to  transfer  direct  between  ships 
and  railroad  cars.  The  small  percentage  of  freight  which 
it  is  possible  to  handle  in  this  manner  is  evidenced  by  the 
location  and  number  of  tracks  on  the  piers  in  this  country. 


CARGO-HANDLING   MACHINERY  227 

It  is  essential,  if  a  large  percentage  of  the  freight  on  a  given 
wharf  is  transferred  directly  between  cars  and  ships,  to 
have  two  or  more  tracks  on  the  edge  of  the  wharf.  Such 
installations,  with  the  exception  of  the  case  in  New  York 
mentioned  in  the  previous  chapter,  are  very  rare  in  this 
country,  but  common  abroad. 


unics       •     i  '•—-lOPib*  transverse  rile  DentsSLfoC. 

All  Piles  H'diom.  &  from    "•  Transverse  Bents  20'CtoC.     Transverse  Column Bents.20C.toC. 

butt.  At  except  those 
under  column  foundations 
art  in  fwo  rows 

A-CONCRETE    CROSS-WALL 


Transverse  Pile  L 
Transverse  Colur, 

TYPE   B  -  EARTH  FILL  ON  PLATFORM 


Substructure  designed  for  a  tw&deck  pier 


Pile  Bents') 

--lOPiles,  '         9Piles    10'CtoC. 

TYPE  C  -  SOLID  EARTH  FILL  TIMBER  PILES 


"Pi!e'Bents.5ttoC 

ALTERNATE  BID -SOLID  EARTH  FILL  CONCRETE  PILES 


IttffConc 

Seams,  \  |     I  Cast-steet 

»r6'ConcrefeSlob      ••    ^Bollard 


9  Piles 
TYPE  0  -COMBINED  TIMBER  AND  CONCRETE  TYPE  E  -  CONCRETE  CROSS  -  BEAM 

Fig.  155.     Comparative  Designs  for  Piers,  Philadelphia,  Pa. 


APPENDIX 

COST   OF  WALLS,   PIERS,   SHEDS,   ETC. 

WALLS 

THE  cost  per  linear  foot  of  the  following  walls  on  the  New  York 
Barge  Cana)  are  based  on  the  unit  contract  prices  and  on  quan- 
tities estimated  from  the  drawings.  They  do  not  include  excava- 
tion or  filling  behind  the  wall.  They  are  all  designed  for  12  feet 
of  water  except  those  at  Buffalo  and  Oswego,  which  were  in  water 
23  feet  deep,  and  at  Gowanus  Bay,  which  provided  for  17  feet  at 
low  tide.  In  the  unit  prices  will  be  found  the  comparative  costs  of 
wooden  piles,  concrete  piles,  steel-sheet  piles  and  concrete  sheet 
piles  which  are  useful  in  estimating  the  comparative  costs  of  piers 
as  well  as  walls. 


N.  Y.  BARGE  CANAL  —  AMSTERDAM:  TIMBER  CRIB  AND  CONCRETE. 
SIMILAR  TO  FIG.  12 


Quantity 

Measure 

Item 

Price 

Amount 

68.3 

Lin.  ft. 

Round  timber 

$  .30 

$20.49 

3.14 

Cu.  yd. 

Stone  filling 

1.75 

5.50 

2.44 

Cu.  yd. 

Second-class  concrete 

7.90 

19.28 

.38 

Lb. 

Structural  steel 

.05 

.02 

1.0 

Lin.  ft. 

Mall.  C.  I.  nosing 

1.00 

1.00 

4.46 

Lb. 

Iron  castings  —  plain 

.035 

.16 

Total  per  lin.  ft. 

$46.45 

230 


APPENDIX 


N.  Y.  BARGE  CANAL  —  FT.  EDWARD:  TIMBER  CRIB  AND  CONCRETE 


Quantity 

Measure 

Item 

Price 

Amount 

.136 

M.  ft.  B.  M. 

Sawed  lumber 

$50.00 

$6.80 

59.7 

Lin.  ft. 

Round  timber 

.20 

11.94 

5.1 

Cu.  yd. 

Stone  filling 

1.60 

8.16 

.015 

Pile 

Mooring  piles 

8.00 

.12 

1.17 

Cu.  yd. 

Second  class  concrete 

6.90 

8.07 

1.00 

Lin.  ft. 

Mall.  C.  I.  nosing 

1.00 

1.00 

.3 

Fastening 

Fender  fastenings 

1.00 

.30 

Total  per  lin.  ft, 

$36.39 

This  wall  was  similar  to  that  at  Amsterdam,  except  that  the 
crib  was  3  feet  higher  and  the  concrete  5  feet  lower.  It  included 
two  longitudinal  strips  of  wooden  fenders. 


N.  Y.  BARGE  CANAL  —  BUFFALO:    SAWED  TIMBER  CRIB  AND  CONCRETE. 

FIG.  15 


Quantity 

Measure 

Item 

Price 

Amount 

.007 

M.  ft.  B.  M. 

Sheeting  and  bracing 

$40.00 

$0.28 

1.0 

Cu.  yd. 

Lining 

1.25 

1.25 

2.0 

Cu.  yd. 

Ballast 

1.50 

3.00 

.740 

M.  ft.  B.  M. 

Sawed  lumber 

50.00 

37.00 

12.31 

Cu.  yd. 

Stone  filling 

.40 

-  4.92 

.633 

Cu.  yd. 

Block  con.,  sec.  class 

9.00 

5.70 

.9 

Cu.  yd. 

Second-class  concrete 

7.25 

6.52 

50.0 

Lb. 

Structural  steel 

.05 

2.50 

1.0 

Lin.  ft. 

Mall.  C.  I.  nosing 

1.25 

1.25 

6.0 

Lb. 

Iron  castings  —  plain 

.04 

.24 

.4 

Each 

Fender  fastenings 

1.20 

.48 

Total  per  lin.  ft. 

$63.  14 

APPENDIX 


231 


N.  Y.  BARGE  CANAL  —  OSWEGO:    SAWED  TIMBER  CRIB  AND  CONCRETE 

FIG.  16 


Quantity 

Measure 

Item 

Price 

Amount 

1.06 

Cu.  yd. 

Ballast 

$1.75 

$1.86 

1.100 

M.  ft.  B.  M. 

Sawed  lumber 

47.00 

51.70 

11.68 

Cu.  yd. 

Stone  filling 

.75 

8.76 

.6 

Cu.  yd. 

Block  concrete 

9.00 

5.40 

.98 

Cu.  yd. 

Second-class  concrete 

7.50 

7.35 

203.0 

Lb. 

Structural  steel 

.03i 

6.60 

1.0 

Lin.  ft. 

Mall.  C.  I.  nosing 

1.20 

1.20 

.5 

Each 

Fender  fastenings 

1.10 

.55 

5.0 

Lb. 

Iron  castings  —  plain 

.05 

.25 

Total  per  lin.  ft. 

$83.67 

N.  Y.  BARGE  CANAL  —  SCHENECTADY:    CONCRETE  RELIEVING  PLATFORM. 

FIG.  39 


Quantity 

Measure 

Item 

Price 

Amount 

.024 

M.  ft.  B.  M. 

Sawed  lumber,  fenders,  etc. 

$50.00 

$1.20 

44.8 

Lin.  ft. 

Foundation  piles 

.25 

11.20 

.1 

Pile 

Fender  piles 

10.00 

1.00 

1.40 

Cu.  yd. 

Second-class  concrete 

8.00 

11.20 

.20 

Cu.  yd. 

First-class  rein,  concrete 

15.00 

3.00 

5.35 

Cu.  yd. 

Third-class  riprap 

3.00 

16.05 

5.8 

Lb. 

Structural  steel 

.05 

.29 

52.3 

Lb. 

Metal  reinforcement 

.035 

1.83 

4.7 

Lb. 

Iron  castings  —  plain 

.035 

.16 

1.0 

Lin.  ft. 

Metal  wall  protection 

.25 

.25 

Total  per  lin.  ft. 

$46.  18 

This  wall  as  built  had  timber  piles  substituted  for  the  concrete 
piles  shown  in  the  illustration.    There  were  some  other  variations. 


232 


APPENDIX 


N.  Y.  BARGE  CANAL  —  WHITEHALL:    TIMBER  RELIEVING  PLATFORM. 

FIG.  40 


Quantity 

Measure 

Item 

Price 

Amount 

.222 

M.  Ft.  B.  M. 

Sawed  lumber 

$55.00 

$12.21 

33.6 

Lin.  ft. 

Foundation  piles 

.35 

11.76 

.1 

Each 

Fender  piles 

11.00 

1.10 

1.1 

Cu.  yd. 

Second-class  concrete 

8.00 

8.80 

4.3 

Cu.  yd. 

Second-class  riprap 

3.50 

15.05 

6.0 

Lb. 

Structural  steel 

.06 

.36 

4.59 

Lb. 

Iron  castings 

.04 

.18 

Total  per  lin.  ft. 

$49.46 

N.  Y.  BARGE  CANAL  —  ROME:    STEEL-SHEET  PILE.     FIG.  63 


Quantity 

Measure 

Item 

Price 

Amount 

.042 

M.  ft.  B.  M. 

Sawed  lumber 

$60.00 

$2.52 

5.71 

Lin.  ft. 

Anchor  piles 

.30 

1.71 

.143 

Pile 

Fender  piles 

13.50 

1.93 

22.3 

Lin.  ft. 

Steel-sheet  piling 

1.20 

26.76 

.02 

Cu.  yd. 

Second-class  concrete 

8.00 

.16 

.407 

Cu.  yd. 

Reinforced  concrete 

15.00 

6.10 

77.0 

Lb. 

Structural  steel 

.05 

3.85 

24.0 

Lb. 

Metal  reinforcement 

.04 

.96 

2.0 

Lb. 

Wrought  iron 

.10 

.20 

8.0 

Lb. 

Iron  castings  —  plain 

.05 

.40 

1.0 

Lin.  ft. 

Metal  wall  protection 

.25 

.25 

Total  per  lin.  ft. 

$44.84 

APPENDIX 


233 


N.  Y.  BARGE  CANAL  —  ITHACA:    CONCRETE  SHEET  PILE.     SIMILAR  TO 

FIG.  65 


Quantity 

Measure 

Item 

Price 

Amount 

.025 

M.  ft.  B.  M. 

Sawed  lumber 

$50.00 

$1.25 

.11 

Pile 

Fender  piles 

11.00 

1.21 

.013 

Pile 

Mooring  piles 

8.00 

.10 

.57 

Cu.  yd. 

Reinforced  concrete 

14.00 

7.98 

46.0 

Lb. 

Metal  reinforcement 

.04 

1.84 

6.0 

Lb. 

Structural  steel 

.06 

.36 

11.0 

Lin.  ft. 

Rein,  concrete  sheet  piles 

1.40 

15.40 

.8 

Lin.  ft. 

Rein,  concrete  square  piles 

1.25 

1.00 

1.28 

Lin.  ft. 

Rein,  concrete  round  piles 

1.50 

1.92 

1.0 

Lin.  ft. 

Metal  wall  protection 

.25 

.25 

Total  per  lin.  ft. 

$31.31 

N.  Y.  BARGE  CANAL  —  ALBANY:    CONCRETE  SHEET  PILE.     FIG.  65 


Quantity 

Measure 

Item 

Price 

Amount 

.086 

M.  ft.  B.  M. 

Sawed  lumber 

$60.00 

$5.16 

1.12 

Cu.  yd. 

Reinforced  concrete 

14.00 

15.68 

5.4 

Lb. 

Structural  steel 

.05 

.27 

184.2 

Lb. 

Metal  reinforcement 

.035 

6.45 

4.6 

Lb. 

Iron  castings,  plain 

.04 

.18 

11.5 

Lin.  ft. 

Rein,  concrete  sheet  piles 

1.45 

16.68 

5.06 

Lin.  ft. 

Rein,  concrete  square  piles 

1.25 

6.32 

2.0 

Lin.  ft. 

Rein,  concrete  round  piles 

1.75 

3.50 

1.0 

Lin.  ft. 

Metal  wall  protection 

.30 

.30 

.31 

Fastening 

Fender  fastenings 

1.00 

.31 

.4 

Pile 

Anchoring  rein.   con.   piles 

to  rock 

7.20 

2.88 

Total  per  lin.  ft. 

$57.73 

The  top  of  the  Albany  wall  was  13  feet  above  mean  water  sur- 
face and  that  of  the  Ithaca  wall  only  3i  feet. 


234 


APPENDIX 


N.  Y.  BARGE  CANAL  —  GOWANUS  BAY,  BROOKLYN:    TIMBER  RELIEVING 
PLATFORM.     FIG.  31 


Quantity 

Measure 

Item 

Price 

Amount 

.192 

M.  ft.  B.  M. 

Sawed  lumber 

$48.60 

$9.33 

66.54 

Lin.  ft. 

*  Foundation  piles 

.27 

17.96 

.092 

Each 

Fender  piles 

10.60 

.98 

1.27 

Cu.  yd. 

Concrete 

6.25 

7.94 

19.6 

Cu.  yd. 

Riprap 

.72 

14.11 

8.5 

Lb. 

Wt.  iron  and  steel 

.035 

.30 

2.5 

Lb. 

Cast  iron 

.03 

.08 

Total  per  lin.  ft. 

$50.70 

BULKHEAD  WALL  —  DEPARTMENT  OF  DOCKS,  NEW  YORK 


Type 

Fig. 

Cost 
per  lin.  ft. 

Depth  of  water 

(Min.   $166.89) 

Rock  bottom 

20 

]  Max.     313.  83  > 

About  36  feet  at  low  tide 

(Av.       260.00) 

(Min.      198.42) 

Hard  bottom 

21 

<  Max.     269.  21  > 

About  13  feet  at  low  tide 

'Av.       238.00) 

(Min.     217.28) 

Deep  Mud,  1876 

44 

]  Max.     392.  27  [ 

About  13  feet  at  low  tide 

(Av.       288.00) 

Deep  mud,  1899 

47 

Av.       278.50 

About  13  feet  at  low  tide 

Includes  dredging,  but  does  not  include  filling  and  other  inci- 
dental work. 

Cost  per  Linear  Foot  of  Principal  Items 


Item 

Rock  bottom  type 

Hard  or  firm  bottom 
type 

Relieving-platform 
type 

Min. 

Max. 

Av. 

Min. 

Max. 

Av. 

Min. 

Max. 

Av. 

Dredging 

$  6.60 
4.50 

156  '.66 

$107.00 
12.50 

309  .'66 

$30.00 
10.40 

254.66 

$11.00 
12.50 
49.00 
125.00 

$44.00 
19.50 
62.00 
133.00 

$32.00 
16.00 
56.50 
129.50 

$13.00 
24.00 
72.00 
88.00 

$62.00 
84.00 
139.00 
139.00 

$30.00 
44.00 
89.00 
109.00 

Riprap  and  cobble  
Piling  and  timber  work  .  .  . 
Concrete  and  granite  

*  Measured  in  place  after  cutting  off.  This  price  was  considered  very  low. 
The  engineer's  estimate  was  32^. 

The  excavation  for  this  wall  cost  $.  185  per  cu.  yd.,  scow  measure,  and  the 
pumped  filling  $.  125  per  cu.  yd.  bank  measure. 


APPENDIX  235 


ITEMIZED  COST  PER  LINEAR  FOOT  OF  A  TYPICAL  SECTION  OF  THE 
WALL  OF  1876.     FIG.  44 

Dredging $32. 41 

Riprap  and  cobble 60. 61 

Piling  and  timber  work: 

Vertical  piling $47. 40 

Bracing  piles 6. 88 

Binding  frames 9. 32 

Sawing  off  piles 4.  76 

Longitudinal  caps 5. 12 

Transverse  caps 8. 37 

Decking 2. 74 

Backing  log  in  place .74 


$85.33 

Masonry: 

Concrete  blocks: 

Fabrication $23. 89 

Setting 9.35 

Filling  chain-holes  . 1 . 64 


$34.88 
Granite: 

Facing $39. 25 

Coping 10.91 

Pointing 1 . 34 

—    $51.50 
Concrete  backing 23. 38 


$109.76 
Total  for  retaining  wall  proper $288. 11 

General  charges: 

Examination  of  the  river  bottom $  .  05 

Removal  of  old  wall 18. 27 

Filling  in  and  grading 10. 19 

Temporary  paved  approach  to  Pier  No.  19 1.19 

Temporary  tool  house,  fences  and  plumbing .07 

Levels  on  an  examination  of  the  wall .14 

Paving 62. 20 

$92.11 
Total  cost  of  improvement $380. 22 

Average  Unit  Costs 

Concrete  blocks  ready  to  ship  per  cu.  yd $7. 44 

Setting  concrete  blocks  per  lin.  foot  of  wall 38. 00 

Bag  concrete  foundation,  deep  rock  type  per  lin.  ft 48. 30 


236  APPENDIX 


CONCRETE  CAISSON  WALL  —  WELLAND  SHIP  CANAL.     FIG.  29 

Caissons,  111  feet  long  cost,  $11,000  each  in  place  or $99.09  per  lin.  ft. 

Concrete  wall  on  top  of  caissons  cost 4. 50  per  lin.  ft 


Total  cost  of  wall  exclusive  of  filling  of  caissons  and  be- 
hind wall $103. 59 

If  filling  of  caissons  cost  25  £  per  cu.  yd.,  the  total  cost 

would  be $112.00  per  lin.  ft. 

It  is  stated  that  the  contract  prices  for  this  work  were  very  low 
and  that  25%  should  be  added  in  estimating  the  cost  of  similar 
work.  This  would  make  the  cost  for  the  wall,  including  filling  of 
caissons,  $140  per  lin.  ft.  The  depth  of  water  is  about  34  ft. 

WALLABOUT  BASIN,  BROOKLYN,  N.  Y. 

TIMBER  RELIEVING  PLATFORM  WITH  WOODEN  SHEET  PILING.    FIG.  34 
Cost  per  linear  foot $80. 00 

STANDARD  CRIB  WALL,  DEPARTMENT  OF  DOCKS,  NEW  YORK.     FIG.  10 

This  wall  costs  about  8^  a  cubic  foot  when  riprap  is  50?f  a  cubic  yard.  This 
would  make  the  wall  shown  in  Fig.  10,  cost  about  $150  per  linear  foot  for  40 
feet  of  water  at  low  tide. 

CLEVELAND  ORE  DOCK  —  CONCRETE  AND  SHEET  PILE.     FIG.  54 
This  patented  wall  is  said  to  have  cost,  per  linear  foot  $28. 40. 

SAVANNAH,  GA  . —  INCLINED  CONCRETE  PLATFORM.     FIG.  41 
Cost  per  linear  foot $50. 00 

A  similar  wall  designed  for  Baltimore  with  reinforced  concrete 
piles  was  estimated  to  cost  about  the  same  as  that  at  Savannah. 


APPENDIX 


237 


PIERS 


Locality 

Fig. 

Type  of  construction 

Cost  per  sq.  ft. 

New  York,  N.Y. 

1 

All  wood 

$1.00  for  single  pile 
row  portion 
$2.50  for  double  pile 
row  portion 

San  Francisco 

Clusters  of  three  timber  piles 
in  cylinder  of   plain   cr  }  re- 
inforced    concrete;      timber 
decks 
Same    as    preceeding     except 
caps  are  of  steel  I  beams 
Single  pil:s  encased  in  plain  or 
reinforced  concrete;    timber 
decks;  steel  I  beam  stringers 
All  wood;    creosoted  piles 

$1.00 
$1.50 

$1.50  to  $2.40 
$.80  to  $1.00 

33d  St. 
Brooklyn,  N.  Y. 

70 

1616'  X  150'  for  one-story  shed. 
Wooden  piles;    wooden   caps; 
concrete  deck  slab;    asphalt 
pavement;    no  side  caps 

$0.97 

35th  St. 
Brooklyn,  N.  Y. 

1740'  X  175'    Wooden    piles; 
wooden  caps;  concrete  deck; 
slab  wooden  side  caps 

$1.08 

29th  St. 
Brooklyn,  N.  Y. 

1199'  X  80'     Wooden     piles; 
wooden  caps;  concrete  deck 
slab;  wooden  side  caps;   as- 
phalt pavement;  no  sewer 

$1.21 

30th  St. 
Brooklyn,  N.  Y. 

1134'  X  125'  Same  as  preceding 

$1.19 

238 


APPENDIX 


PIERS  —  Continued 


Locality 

Fig. 

Type  of  construction 

Cost  per 
sq.  ft. 

Philadelphia:     Piers     38 
and  40  tentative  bids 
for  comparison  of  costs. 
Riprap    added    and 
other  corrections  made 
to  bring  all  on   same 
basis  for  comparison 

155 

551'  X  180'  for  two-story  sheds. 
Type  A.    Wooden  piles;  con- 
crete cross  walls  and  deck 
Type  B.    Wooden  pile  platform 
supporting  concrete  walls  and 
earth  fill 
Type  C.     Solid  fill 
Alternate.     Concrete  piles 
Type    D.      Wooden   piles    and 
caps;    concrete  deck  slab 
Type  E.     Wooden  piles;    con- 
crete posts,  cross  beams  and 
deck 

$2.87 

3.07 
3.02 
3.32 

2.43 
2.51 

New  York,  Pier  New  No.  1 

Concrete  cross  walls  on  rock 
bottom;  concrete  arches 

14.00 

New  York,  Pier  A 

Concrete  cross  walls  on  rock- 
bottDm;  steel  girders,  concrete 
arches 

11.60 

Bocas  del  Toro,  Panama 

77 

Concrete  —  protected,  wooden 
piles;  concrete  deck  beams; 
concrete  slab 

2.13 

Brunswick,  Ga. 

81 

Concrete  piles;  wooden  caps, 
bracing  and  deck 

1.40 

Charleston,  S.  C. 

Concrete  piles;  wooden  caps, 
bracing  and  deck 

2.60 

Oakland,  Cal. 

83 

Concrete  piles;  concrete  beams 
and  deck 

$3.25 

Halifax  Pier  2,  1.  C.  R. 

84 

Concrete  piles,  beams  and  deck 

2.89 

Puget  Sound  Navy-yard, 
Washington,  Pier  8 

Concrete  columns,  steel  deck- 
beams,  concrete  deck-slab 

3.32 

San  Diego,  Cal. 

130'x800'    Concrete  columns, 
single  wooden  pile  under  each 
column;  steel  beams  cased  in 
concrete;  concrete  deck 

3.36 

Olongapo,  P.  I. 

88 

Concrete  columns;  steel  deck- 
beams;  concrete  deck-slab 

2.60 

Balboa,  Canal  Zone 

90 

Concrete  columns,  beams  and 
deck 

3.28 

APPENDIX 


239 


UNIT  PRICES  IN  TENTATIVE  BIDS  FOR  PHILADELPHIA  PIERS  38  AND  40 

1913-14 

FIG.  75     (All  prices  are  for  materials  in  place  in  the  work) 


Types 

"A", 

and' 

"B" 

<C" 

"D" 

and  "E" 

Alternate 

Gravel  or  cobble  filling,  per  ton.  . 
Riprap  per  ton      .          

$  .65  to 
1  50 

$  .80 
2.25 

$  .50 

to    $  .75 

$1  25 

Piles                              

16.00 

20.00 

14  00 

20  00 

21  00 

Spur  piles    

18.00 

33.55 

15.00 

25  00 

23  80 

12  in.  sheet  piling,  per  ver.  lin.  ft. 
Timber,     clamps,      caps,     wales, 
decking 

0.70 
47.00 

1.25 
70  20 

52.00 

70  00 

.80 
65  00 

White  oak  fenders,  per  1000  ft. 
b  m 

70  00 

98  40 

65  00 

87  00 

70  00 

No.  1  reinforced  concrete,  per  cu. 

yd.  .                        

11.00 

20.00 

11  00 

15.00 

11.00 

No.  2  mass  concrete,  per  cu.  yd..  . 
Reinforcement  per  ton 

6.50 
45.00 

11.05 
100.00 

7.00 
40  00 

10.00 
100  00 

10.00 
70  00 

Structural  steel,  per  ton  

50.00 

100.00 

55.00 

100.00 

80.00 

PIER  SHEDS 


Locality 

Fig. 

Dimensions  and  Type 

31st  St.,  Brooklyn,  N.  Y. 

One  story  1452'  X  141'  8£ 

$0.75 

33rd  St.,  Brooklyn,  N.  Y. 

Ill 

Steel  frame,   gal.  iron  siding; 

gravel  roof  on  plant;  wooden 

doors  1593'  x  141'  8| 

0.98 

New  York  Dock  Co. 

108 

One  story  461'  X  66'.    Wooden 

Brooklyn,  N.  Y. 

frame,     gal.     iron     siding; 

.95 

gravel  roof 

Halifax,*  Pier  No.  2,  I.  C.  R. 

84 

Two-story  Reinforced  concrete 

2.07 

*  The  interior  fittings  of  the  offices,  waiting  rooms,  etc.,  which  occupy 
68,392  sq.  ft.,  including  heating,  lighting,  water  piping  for  fire  protection  for 
the  whole  of  the  two  stories,  cost  $105,716,  or  $1.54  per  sq.  ft.  in  addition  to 
the  above. 


240  APPENDIX 

Cost  of  Steel  Sheds  per  Cubic  Foot 

With  steel  at  $60  per  ton,  erected,  the  cost  of  steel  sheds  as 
stated  by  Mr.  S.  W.  Hoag,  Jr.,  in  1905,  was  as  follows: 

Single  story  shed,  exclusive  of  offices,  etc 3.8  £  per  cu.  ft. 

Two-story  shed,  exclusive  of  offices,  etc 6. 25ff  per  cu.  ft. 

Office  portion;  one  or  two  story  sheds 10^  per  cu.  ft. 

MISCELLANEOUS 

Concrete  Columns.  San  Francisco  —  Piers  30  and  32,  1912, 
3'  10"  diam.,  $3.15  per  lin.  ft.;  3'  6",  $4.93;  4'  0",  $4.58. 

Creosoting  Yellow  Pine  Lumber.  $8.00  to  $10.00  more  per 
thousand  feet  board  measure  for  creosoted  lumber  in  place  than 
for  untreated  were  bid  in  1916  for  the  repair  and  extension  of 
pier  6,  East  River,  New  York,  N.  Y. 

uGunite"  Protected  Piles.  Covering  piles  with  two  inches  of 
cement  mortar,  by  means  of  the  cement  gun,  cost  63  ff  a  linear  foot 
of  pile  on  the  Pacific  Coast. 

Creosoted  Piles.  Fourteen  pounds  of  creosote  to  the  cubic  foot 
of  timber  cost  27  ff  on  the  Pacific  Coast.  Another  authority  gives 
15  to  20^  per  linear  foot  with  creosote  at  from  7.69^  to  10.04^ 
a  gallon. 

Granite.  Granite  for  facing  the  bulkhead  wall  in  New  York 
cost,  in  1912,  about  $1,  cut  and  delivered  ready  to  set.  Setting 
cost  about  40^f  exclusive  of  pointing. 

Fire  Protection.  A  dry-pipe  sprinkler  system  for  the  freight 
sheds  with  wooden  trusses  and  roofs  and  hollow  tile  walls,  recently 
constructed  for  the  Municipal  Docks  at  Astoria,  Ore.,  cost  for 

2,550  sprinkler  heads $12,000.00 

Fire  hydrants,  standpipes,  water  main  and  a  50,000 

gallon  tank  cost 8,500.00 

$20,500.00 

A  portion  of  the  freight  sheds  was  two  stories  high  and  the 
area  served  by  the  sprinklers  was  130,170  square  feet  or  about 
51  square  feet  to  each  sprinkler. 

The  $12,000  covered  valves,  air-compressors,  piping  and  all 
portions  of  the  system,  except  the  supply  mains  and  tank  and 
painting  and  frost-proof  covering  for  the  pipes,  and  figures  out 
at  $4.70  per  sprinkler  and  $0.0922  per  square  foot  of  floor  area. 


APPENDIX  241 

The  total  cost  of  the  fire  protection  per  square  foot  including 
tank,  hydrants,  stand-pipes  and  mains,  but  not  including  paint- 
ing and  pipe  covering  was  about  $0.1575. 

The  tank  and  its  supporting  frame  were  of  wood  and  cost 
$1,877.40. 

Fire-proofing  Steel  Pier  Shed  Trusses  with  Mortar,  Balboa, 
C.  Z.,  Fig.  103.  Eighty-four  main  trusses  of  80-feet  span 
spaced  17  feet  apart  together  with  the  monitors  and  longitudinal 
trusses  required  about  12,000  square  yards  of  expanded  metal 
and  564  cubic  yards  of  mortar.  The  cost  of  putting  the  ex- 
panded metal  in  place  was  about  8^  per  square  yard  and  the 
mortar  cost  $18.33  per  cubic  yard  in  place  with  cement  at  $1.17 
a  barrel,  sand  at  86  f£  cubic  yard  and  common  labor  at  13  ff  an 
hour.  West  Indian  labor  was  used. 

If  20^  a  square  yard  is  allowed  for  the  expanded  metal,  the 
cost  figures  out  about  $13,688.00  for  about  116,000  square  feet 
of  area  or  something  less  than  12  j£  a  square  foot. 

Inclined  Conveyor.  Inclined  conveyors  on  the  Municipal  Dock 
at  Astoria,  Ore.,  cost  $3,000. 00  each,  including  steel-trussed  beams, 
all  mechanical  equipment,  and  power  transmission. 


INDEX 


Alarms,  automatic  fire,  195,  198 
Algoma,  caisson  breakwater,  76 
Annual  charge,  21 
Armature  plates,  35 
Asbestos-protected  steel,  167 
Ashtabula  Harbor,  horizontal  sheet- 
ing, 105 
Asphalt,  120,  123,  141,  148,  192,  237 

block  pavement,  192 
Atlantic  City,  steel  pier,  14,  134,  138 


Backing  logs,  37 

Balboa,  concrete  columns,  152 

fire-proof  steel  trusses,  164 
Baltimore,  pier  failure,  32 

concrete  sheet-pile  wall,  108 
Barge  Canal,  boats,  3 

crib  wall,  55,  58,  59 

mass-concrete  walls,  69 

platform  walls,  85 

steel,  sheet-pile  wall,  108 
Binding  frame,  89 
Bitts,  38,  189 

Blackrock,  steel,  sheet-pile  wall,  104 
Block-and-bridge  piers,  3,  112,  154 
Bocas  del  Toro,  pier,  128 
Bollards,  38,  189 
Bolts,  drift,  40 

expansion,  41 

galvanized,  40,  84 

screw,  40 

Boring  under  water,  96 
Borings,  32 

Boston  &  Albany  R.R.  piers,  119 
Boston,  pier  with  concrete  caps  and 
deck,  124 

quarried  stone  wall,  6 

solid-filled  pier,  156 


Bracing  piles,   30,   35,   84,   93,    103, 

105,  137,  141,  143,  235,  239 
Bracing,  transverse,  35,  130,  134,  141, 

147,  151 

Brick  pavement,  193 
Brooklyn,  navy  yard  piers,  127 

33d  St.  pier,  123,  237 

35th  St.  pier  shed,  176,  239 
Brunswick,  concrete-pile  pier,  136 
Buckets,  fire,  195 
Bulkhead  line,  27 

wall,  90 
Bush  Terminal,  platform  wall,  86 

solid-filled  piers,  155 


Caissons,  floating,  71,  72,  74,  76,  236 
Calculation  of  pressures,  43 
Canal  boats,  202 
Cargo  booms,  203,  204 
Cargo-hoists,  New   York,   211,   216, 

217 

Cast  iron,  16,  136 
Cement  £un,  132,  240 
Central  R.R.  of  N.J.,  crib  wall,  54 

cribs  in  pile  pier,  124 

pier,  124 
Charleston,  concrete  columns,  149 

concrete-pile  pier,  137 
Chelsea  district,  New  York,  19 
Chelsea  piers,  sheds,  161,  180 

doors,  170 
Chicago,  platform  wall,  94 

sheet-pile  bulkhead,  103 
Cienfuegos,  cast-iron  cylinders,  136 
Cleats,  188 

Cleveland,  platform  wall,  98 
Cofferdam,  cylindrical,  146,  151 
Columns,  13,  141,  145,  149,  150,  151, 
152 


243 


244 


INDEX 


Combination  piles,  18,  128,  132 
Commercial  life,  14,  19 
Comparative  estimates,  20,  122,  228, 

239 

Composite  piles,  18,  128,  132 
Concrete,  5,  11,  17,  90 
blocks,  156 

blocks,  cost,  230,  231,  235 
block  walls,  62 
caissons,  71,  72,  74,  76 
caisson  wall,  cost,  236 
columns,  cost,  240 
columns,  13,   141,   145,  149,  150 

151,  152 
cost,  5,  17 
cribwork,  60 

deposited  under  water,  13 
filled  crib,  59 
-   in  bags,  62,  235 
in  sea  water,  12 
mattress,  63,  90 
piles,  13,  52,  136,  138,  139,  140, 

143,  144,  145 
round,  cost,  233, 
sheet-cost,  233 
square,  cost,  233 
pipe  for  sewers,  42 
protected  piles,  18 
reinforced,   cost,  231,  232,  233, 

239 

sheet-piles,  13,  82,  109,  110 
tile,  168 
vs.  timber,  17 

Coney  Island,  iron  pier,  14,  134 
Controllers,  portable,  204,  213 
Conveyors,  inclined,  truck,  215,  222, 

241 

portable,  204,  213 
Copenhagen,  caisson  wall,  71 
Corrosion,  14,  132 
Corrugated  iron,  166 
Cost 

binding  frames,  235 
caisson  wall,  236 
cobbles,  239 
concrete,  5,  17 

blocks,  230,  231,  235 
columns,  240 


in  bags,  235 
piles,  round,  233 
square,  233 
sheet,  233 

reinforced,  231,  232,  233,  239 
conveyors,  inclined  truck,  241 
creosoting  lumber,  240 
crib  wall,  230,  236 
equal  volumes  of  concrete  and 

lumber,  18 
excavation,  234 

fender,  piles,  231,  232,  233,  234 
fire-proofing  trusses,  241 
fire  protection,  240 
granite,  234,  235,  240 
"gunite  "-protected  piles,  240 
lumber,    sawed,   230,    231,   232, 

233,  234,  239 
metal   reinforcement,   231,    232, 

233,  239 

piers,  131,  237,  238,  239 
piles,  231 

bracing,  235,  239 
fender,  231,  232,  233,  234 
concrete,  round,  233 
sheet-,  233 
square,  233 
creosoted,  240 
"  gunite  "-protected,  240 
steel,  sheet-,  232 
timber,  231,  232,  234,  235, 

239 

timber,  sheet-,  239 
pumped  filling,  234 
repairs  to  wooden  piers,  5 
riprap,  231,  232,  234,  235,  239 
sawed  lumber,  230,  231,  232,  233, 

234 

sawing  off  piles  under  water,  235 
sheds,  239,  240 
sheet-piling,  steel,  232 
splicing  piles,  6 
telphers,  225 
timber,  round,  229,  230 
unloading  steamships,  223 
walls,  229 

Crib  wall,  Barge  Canal,  55 
Buffalo,  sawed  lumber,  58 


INDEX 


245 


Communipaw,  54 

concrete,  60 

concrete-filled,  59 

cost  of,  52,  230,  236 

Duluth,  56 

New  York,  53 

on  piles,  84 

Oswego,  sawed  lumber,  59 

Two  Harbors,  Minn.,  57 
Cylinders,  metal  for  piers,  132, 135, 136 
Cylindrical  cofferdams,  146,  151 
Cranes,  166 

floating,  203 

gantry,  206 

hatch,  203,  206 

portal,  206 

revolving,  206,  215 

roof,  209 

semi-portal,  206 

straight  line,  217 

travelling,  166,  204 

vs.  ship's  gear,  215 

wharf,  206,  215 

D 

Decay  of  timber,  4,  5,  6,  11 

Decks,  elevation  of,  25 

Depot  Harbor,  concrete  cribwork,  60 

Depreciation,  21 

Details  of  construction,  33 

Detroit,,  platform  wall,  97 

Dimensions  of  wharves,  24 

Diving  bell,  69 

Dock  spikes,  41 

Doors,  for  sheds,  168 

rolling,  173 
Douglas  fir,  7 
Down  spouts,  168,  177 
Drift  bolts,  40 
Duluth,  solid-filled  pier,  158 
Durability  of  timber,  5,  6,  33,  34 

E 

Elasticity  of  wharves,  8,  183 
Elevation  of  decks,  25 
Elevators,  hatch,  203 

inclined  truck,  215,  222,  241 
Expansion  bolts,  41 


Fastenings,  iron  and  wood,  40 
Fenders,  38,  70,  183 

continuous,  184 

for  corner,  38,  184 

floating,  186 

of  saplings,  186 

spring,  185 

suspended,  186 
Filling,  pumped,  cost,  234 
Fire,  8 

Fire-proofing  steel  trusses,  165,  241 
Fire  protection,  194 

cost,  240 
Fire  walls,  195,  196 

buckets,  195,  198 
Floating  caissons,  71 
Followers,  pile,  31,  150 
Formulas,  pile,  28 
Fortress  Monroe,  iron  pier,  16,  133 
Fort    Mason,    piers    with    concrete 

columns,  149 
Freight  sorting,  193,  201 

G 

Galvanized  bolts,  40,  84 
Gliding  switch,  211 
Gowanus  Bay,  platform  wall,  77 
Granite,  61,  62,  63,  154,  156 

cost,  234,  240 

mooring  post,  187 
Gravity  walls,  48 
Growth  of  ships,  22 

H 

Halifax,  concrete-pile  pier,  141,  142 

concrete-block  wall,  63 

concrete  shed,  180 

solid-filled  pier,  156 
Hamburg,  25 
Hamilton,  capping  piles,  98 

steel  sheet-piling  14,  100, 
Hammers,  pile,  29,  142,  145 
Hand  rail,  174 
Hatches,  in  pier  decks,  196 
Havana,  concrete-pile  piers,  141,  143 

concrete  pier-shed,  176 
Heavy  packages,  203 


246 


INDEX 


Hoboken,  piers,  125 
Horizontal  bracing,  35,  141 
Hunt's  Point,  platform  wall,  79 

I 

Iloilo,  152 
Inclined  piles,  30,  35,  84,  93,  103,  105, 

137,  141,  143,  147,  235,  239 
Iron  piles,  134 

J 

Jacksonville,  platform  wall,  101 
Jetting,  134,  136,  138,  139,  141,  145, 

150,  151,  154 
Joists,  40,  119,  196 


Lagged  piles,  29     . 

Lambert's  Point,  iron  pier,  134 

steel  pier,  136 

Lateral  support  for  piles,  31 
Life,  commercial,  4,  19 
Lighting,  for  sheds,  168 
Limnoria,  9 
Live  loads,  26,  78 
Load  factor,  201 

Long  Branch,  concrete-pile  pier,  139 
Los  Angeles,  platform  wall,  82,  87 
Loss  of  income  during  repairs,  21 
Loss  of  income  after  fire,  21 
Lumber,  sawed,  cost  of,  230,  231,  232, 
233,  234,  239 

creosoting,  cost  of,  240 

M 

"Maine,"  wreck  of,  16 
Manila,  steel  pier,  135 
Marginal  wharves,  23 
Marquette,  solid-filled  pier,  157 
Mass-concrete  walls,  69 
Mattress,  concrete,  63,  90 
Metal  piles,  132,  138 
Mooring  posts,  cast-steel,  189 

corner,  38,  188 

granite,  187 

reinforced  concrete,  189 
Mooring  rings,  190 
Mud  waves,  48 


N 

New  London,  pier,  120 
New  York 

block-and-bridge  piers,  154 

concrete-block  walls,  62,  63 

crib  wall,  53 

design  for  solid-filled  pier,  155 

mass-concrete  wall,  69 

pier  sheds,  161,  170,  176,  181 

recreation  piers,  162 

relieving  platform  walls,  79,  88, 
92,  93,  94 

riprap  wall,  50 

wooden  piers,  33,  118 
Xorre  Sundby,  caisson  wall,  72 
North  German  Lloyd,  concrete-filled 
crib,  59 

piers,  4,  118 

pier  sheds,  166 


Oakland,  mass-concrete  wall,  69 

concrete-pile  pier,  140 
Obsolescence,  21 
Old  Orchard,  steel  pier,  14,  135 
Old  Point    Comfort,    iron    pier,    16, 

133 
Olongapo,  concrete  columns,  150 


Pavements,  148,  191 

asphalt  blocks,  192 

brick,  192 

Philadelphia  piers,  115,  127 
Pier  failure,  Baltimore,  32 
Pier-head  line,  27 
Piers,  angular,  23 

block-and-bridge,  31,  112 

cost,  131,  237,  238,  239 

pile-platform,  3,  112,  113 

recreation,  162 

solid-filled,  4,  112,  155 

stsel,  14,  135 

types,  3 

width  of,  25 

wooden,  34 
Pier  sheds,  159 

Chelsea,  161 


INDEX 


247 


concrete,  176,  178 

cost,  235 

covering  for,  166 

doors,  168 

down  spouts,  168,  177 

fire  proofing  of  trusses,  165 

North  German  Lloyd  Co.,  165 

posts,  165,  177,  178,  182 

Tehuantepec  Railway,  162 
Pile  drivers,  29,  141,  148,  149 

followers,  31,  150 

formulas,  28 

hammers,  29,  142,  145 
Piles,  9,  13,  18,  28 

combination,  18 

cost  of,  18,  231,  232,  239 

creosoted,  9 

fender,  cost  of,  231,  232 

composite,  18,  128,  132 

concrete,  13,  52,  136,  138,  139, 
140,  143,  144,  145 

concrete-protected,  18 

concrete    sheet,     13,     82,     109, 
110 

inclined,  30,  35,  84,  93,  103,  105, 
137,  141,  147,  235,  239 

lagged,  29 

lateral  support  for,  31 

metal,  132,  138 

splicing,  cost  of,  6 

steel  sheet-,  14,  97,  101,  105,  108, 
155,  158,  232 

sawing  off,  cost,  235 

test,  32 

Plaster  board,  120,  162,  168 
Port  au  Prince,  pier,  18,  128,  131 
Porto  Rico,  concrete-protected  piles, 

18,  132 

Providence,  platform  wall,  83 
Puget  Sound,  concrete  columns,  151 


Quarried-stone  walls,  61 

R 

Railroad  tracks,  192,  226 
Ramps,  portable,  193,  224 
Recreation  piers,  162 


Reinforcement,  metal,  cost,  231,  232, 

233,  239 

Relieving  platform  walls,  76 
Reservoirs  in  freight  handling,  222 
Rio  Janeiro,  platform  wall,  86 
Riprap,  17,  44,  45,  49,  62,  63,  67,  77, 

95 

Riprap,  cost,  234,  239 
Rolling  doors,  173 
Rome,  steel  sheet-piling,  108 


San  Diego,  mass  concrete  wall,  71 

Sandusky,  steel  sheet-piling,  105 

San  Francisco,  concrete-pile  pier,  145 
composite-pile  pier,  131 
pier  on  concrete  columns,  147 
riprap  wall,  51 

Santa  Monica,  concrete-pile  pier,  138 

Saplings,  used  for  fenders,  102,  186 

Sap  wood,  7,  11 

Savannah,  platform  wall,  85 

Schenectady,  platform  wall,  85 

Screw  bolts,  40 

Seattle,  two-story  shed,  174 

Sewer  boxes,  123 

Sewers  in  piers,  42,  138 

Sheet-pile  walls,  103 

Sheet-piling 

concrete,  13,  82,  109,  110,  233 
horizontal  resistance  of,  48 
steel,  14,  97,  101,  105,   108,   155, 

158,  232 

wood,  82,  83,  87,  94,  97,  98,  103, 
239 

Sheds,  concrete,  176,  178,  180 
cost,  239,  240 
fire  protection,  194 
Tehuantepec  Railway,  162 
trusses  for,  steel,  175,  176,  179, 

180,  182 

trusses  for  wood,  174,  179 
wharf  and  pier,  159 

Ship's  gear,  204 

Ships,  growth  of,  22 

Side  caps,  35,  124 

Side  ports,  202 

Sinking  fund,  21 


248 


INDEX 


Skids  for  electric  trucks,  213 

Slips,  width  of,  25 

Solid-filled  piers,  4,  155 

Sorting  of  freight,  193,  201 

Speed  limiting  points,  221 

Spikes,  dock,  41 

Splicing  piles,  cost,  6 

Sprinklers,  automatic,  162,  195,  196 

cornice,  196 
Steel,  14 

piers,  14,  154,  135 

piles,  109 

sheet-piling,  14,  97,  101,  105,  108 

sheet-pile  walls,  105,  108 
Stone  masonry,  14 
Suez  Canal,  22 

depth  of,  22 
Switch,  gliding,  211,  225 


Table  of  live  loads,  26 

Tampico,  steel  wharf,  135 

Tehuantepec  Railway,  pier  shed,  162 

Telphers,  166,  193,  203,  210,  224,  225 

Teredo,  9 

Test  piles  and  borings,  31 

Tidal  prism,  2,  26 

Timber,  4 

decay  of,  4,  5,  6,  11 
durability  of,  5,  6,  33,  34 
round,  cost  of,  229,  230 

Toledo,  platform  wall,  97 

Tonnage  of  vessels,  increase  in,  22 

Toronto,  steel  sheet-piling,  97 

Transfer,  direct  between  vessels  and 
cars,  193,  194,  226 

Transverse  bracing,  130 

Travelling  cranes,  166 

Treenails,  40,  84,  92 

Trucks,  two-wheeled,  200,  202,  203, 
223 


four-wheeled,  200,  203 
electric,  202,  204,  213,  223 
horse,  225 
T  Wharf,  23 

V 

Ventilation  of  piers  4,  120 
Victoria,  B.C.,  caisson  wall,  74 
solid-filled  pier,  156 

W 

Wallabout  Bay,  platofrm  wall,  82 
Walls,  concrete  block,  62 

cost  of,  229 

floating-caisson,  71 

function  of,  43 

fire,  195,  196 

gravity,  48 

mass-concrete,  69 

pressures  on,  43 

quarried  stone,  61 

relieving  platform,  76 

sheet-pile,  103 

types,  3 

Watchmen's  clocks,  199 
Water  curtains,  195 
Water  jetting,  134,  139,  141,  151,  154 
Weight  of  riprap,  45 
Welland  Canal,  caisson  wall,  72 
Whale  Creek,  platform  wall,  84 
Wharf  drops,  190 
Wheel-guards,  173 
Whitehall,  platform  wall,  85 
Width  of  piers,  25 

slips,  25 

Winches,  203,  204,  206,  212 
Wired  glass,  168 
Wire  nails,  37 
Wooden  piers,  34 
Wood  preservatives,  9,  33 


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